Your views on the familiar are a bit idealized I think.
For my sagas, familiars are individuals. Most of the time, those individuals are not interested in lab work. To get help, the maga may have to bargain. She probably can count on the familiar for longevity rituals and empowering the bond, but probably not much. It will be difficult to ask them to study magic theory books alone for a season (Ha! Whatever!). However, I agree it may depend on the familiar.
Moreover, familiars have drawbacks. One can have arguments with her familiar. The familiar may get targeted or kidnapped. Or even get killed. From time to time, it's a source of problem. Perhaps your familiar will cheat (and stole vis for his consumption), or he will fight other familiars, or even magi. Perhaps, he will travel alone from time to time. Perhaps he don't like when you help those petty humans and will try to convince you to act as he prefer?
My view is heavily influenced by the 4th edition, I think. If you don't see the familiar only as a tool, then suddenly it's not overpowered anymore... unless your familiar is called Sordus, of course.
Something to keep in mind here- RAW, nothing prevents a bjorner from having an animal friend- indeed it would be very much in character for them to have one. A wolf bjorner might have a pack mate, a raven, or so forth. A magical animal friend who learns magic theory can still serve as a lab assistant, and do many of the things a familiar does, the major difference is that it cannot have the three cords.
Again given the bjorner history regarding the binding of spirits, it seems to me there is a very strong cultural reason for them to not have a familiar bound by the three cords.
I don't see anything in the books that suggest Bjornaer magi would have a cultural problem with familiars.
The witch-cult that Birna came from supposedly enslaved spirits and could then take their shape, and this is why House Bjornaer are very suspicious of shapeshifters. While it would not be unreasonable to extend that suspicion to any binding of spirits, I can't find anything to suggest this is actually the case.
Case in point: Birna was close friends with Merinita, even though Merinita was the one who introduced the binding of familiars to the Order. I really doubt they would have been close friends if Birna had thought there was something wrong about binding a familiar.
Keep in mind that a familiar must agree to be bound - it is a voluntary bond which works both ways, not enslavement or servitude.
I must admit, I thought not having the cords is the big deal. I didn't realise in Monty Hall Ars Majica a familiar is also a lab assistant.
I'm a fan of Laurent's interpretation. A familiar is a living being with it's own goals and desire. The familiar probably doesn't have a desire to spend 2 seasons studying with the companion with good teacher puiisant and affinity in teaching, communication 5, magic theory 6, etc.
If a group is going the full monty hall, does game balance even matter at that point?
Familiars do tend to share certain personality traits with their mage though.
And I agree, much as I love playing in the lab, I too tend to think this can get out of hand very quickly.
That's not Monty Hall, that's straight out of core.
It's a pretty fundamental part of why everyone's been talking up the power and usefulness of familiars for years. Maybe have a look at Anulis Connectens?
The Cords are awesome. Having someone you can trust, effectively allowing you to act in multiple places at the same time can be useful. An assistant in the lab can be very useful, especially one that does not count against the number of assistant that you can normally have.
But to me, all of that pales next to the ability to invest the Bond with effects that do not cause Warping!
yes, the familiar is a character, not having the bonds doesn't change that. My point here is that the bonds are the only aspect of a familiar which are missing for a bjorner.
Also there is space between "forging bonds is evil and I must oppose the magus who introduced the idea" and "I'm not comfortable doing this given my background of running away from people who enslaved animal spirits to change shapes"
It would be like coming out of the pre-civil war south and recognizing that BDSM is a valid lifestyle choice but not being comfortable being a dom because you have seen real slavery.
I see your point, but
a) Apart from Birna herself few if any Bjornaer magi will have any personal experience with the enslavement of animal spirits
b) The binding of a familiar is a bonding of willing equals, not that of master and servant (let alone master and slave.)
My opinion is that it is unbalanced to not allow Bjornaer to take familiars. Familiars are just too critical for the long term development of the magi. To be denied the assistance of the familiar is a huge drawback, neither becoming your heart beast at will nor being part of a good mystery cult comes remotely close to counter balancing it.
Is there anything explicitly stating this? I thought the list was familiars, failed apprentices and people with the Gift and a score of at least 1 in Magic Theory. In theory you could have a Magical Animal Friend with the Gifted magical quality, but that doesn't feel like it would be the default.
No, Magical Animal Companion (and related) hasn't ever shown up on the list to my knowledge. Your list is mostly complete. You can also do lab work as a Becoming-Faerie, despite no longer having the Gift. Also, a Magic being that has the Gifted Quality can, as that's basically the same as having the Gift; mostly it was to put a value on the valuable, 0-cost Virtue that the Gift is.
My impression at least is that any being of the magic realm can act as a lab assistant, though it is not specified. While there are several things which are specified as being able to serve as laboratory assistants, nothing is specified to not be able to serve, leaving a huge area of YSMV.
ArM5 Core, p. 103 defines a list of who can assist in the lab. As far as I can tell from the phrasing (being not a native speaker of English), this is is very much a list of permissions, meaning that anyone not explicitly permitted to assist in the lab, cannot.
In that case why restrict yourself to beings of the magic realm? There is nothing explicitly saying that beings from the Infernal, Divine, or Faerie realms can't assist either, just as there is nothing explicitly saying you can't have a random mudcaked peasant assisting you in the lab.
My reading of the rules is different. If there is a list of beings that can assist in the lab (which there is) then, unless otherwise noted, any being not on that list can't.
This is a topic which has been discussed as nauseum, the rules are fairly explicit that the list is not inherently exhaustive- in part because it is not presented as a list but rather each person who can help is listed separately. p. 103 indicates anyone who is Gifted and has magic theory of 1 can help= failed apprentices are described elsewhere and under the virtue it is noted they can help in the lab. Additionally there are forge companions who can aid Verditius mages which was left off of your list. It is fairly well implied that there at least are demons who can help in the lab, though accepting that help could get you marched and that might be the least of your problems... certainly Jinn aid the the magis of Seuleman, and it is implied this assistance could apply to Hermetics as well...