Combining the rules for magical immortal magi from TMRE and RoP:Magic character advancement and management rules requires some thought. How do you manage the issue ?
Some issues that come to my mind:
Are immortal magi still be protected by the Oath or not ? According to TMRE, it seems that the legal status of living ghosts is somewhat more precarious, since they technically died and their Oaths expired. OTOH, they could re-swear their Oaths and re-join the Order. About alchemical immortals and Aspects of Daimons, they never died, only underwent a mystical transformation, so it is difficult to see what would terminate their membership. Is there any legal precedent that states Order membership be limited to "living mortal humans" ? IIRC, there is none. While there are going to be several mages that would prefer to strip immortal fellows from protected status in order to be free and sack their resources, and not to have them as political top dogs, OTOH there are going to be many other mages that would feel protective of their immortal elders (Bjornaer, Criamon, Merinita, theurgists come to mind) and/or look forward to possibly becoming immortal themselves.
About the potentially controversial issue of studying times, it appears that immortal magi, while not liable to death by deprivation, are still hampered by lack of sleep (since they cannot recover Fatigue or Might if deprived), so they would still be limited to the usual four seasons. However, they have an advantage here since they can make extensive use of unsual lab schedules without fearing Aging or Warping side-effects. A little balance to their serious learning penalties.
About learning, a big issue is whether magical immortals can consume vis in order to "fix" their learning, as an alternative to talisman-binding, or not. IMO they do, and talisman-binding and vis-consumption are alternative means of performing the same process. Talisman-binding is just an alternative way of fixing learning, which hermetic magic allows to magical immortal magi.
Concerning Acclimation, it seems that magical immortal magi would still be liable to it. This is no real problem for Daimons, who are permanent residents of the Magic Realm anyway, and only send temporary Aspects to earth, and it may be a serious problem for Living Ghosts who raise their Might beyond which the magical aura of their Haunt may sustain. They would then be forced to make periodical vis-hunting forays in possessed bodies, unless they can establish their Haunt in a covenant.
Alchemical beings have a choice of taking residence in a strong magical aura, sacrificing some seasons of study by spending them in the Magic Realm, or using the bond-effect route. Alchemical immortals have less problems than living ghosts about taking residence in a covenant, which would pretty much settle the Acclimation issue through the bond-effect route. Solitary and reclusive immortals would have to seek residence in an Aura, although I surmise that training an apprentice would work to satisfy the bond-effect requirements. Vis consumption ought to be only a last-ditch option, except maybe for living ghosts.
OTOH, it must be remarked that if a powerful magical immortal can stave off Acclimation by other means, the place where he settles down shall necessarily develop or increase its Magical Aura substantially over time, and this is going to be a rather useful boon for magical immortals.
A note about familiars: it appears that immortal magi are no longer able to sustain their familiars against Acclimation. Even if the familiar may gain immortality this way (here assuming that all magical animals that are interested in the familiar bond are burdened with the Age Quickly Flaw), they need an Aura or vis consumption, although covenant residence might fulfill the effect acclimation-staving method for them, too.
Another very important issue is whether Daimons are free to send their Aspects to earth on their own initative, even in the lack of a summoning through Invoke spells, or a familiar bond. IMO, even if it is not explicitly stated, it is not explicitly forbidden either, so Aspects are free to roam the Earth to fulfill their Daimon's agenda. It's just that such forays earn the Daimon no advancement points, so they are not as profitable as answers to summons.
By the way, since advancement points are just the equivalent of the vis spent in the summoning ritual spell, it appears that they are just another way of expressing learning by vis consumption, a specialized way of doing it like talisman binding. Following this line of reasoning, Aspects could roam the Earth to hunt vis to allow learning for their Daimons. It is not clear, however, whether Daimons could make use of the vis their Aspects forage on earth and bring to the MR to undergo Transformation.
RoP:M established beyond doubt that magical immortals can still make Initiations through Mystery Rituals, even if in most cases magical beings find Virtue development by transformation much easier than mortal beings that are restricted to Initiation (yet another major boon of the magical nature). It also appears that vis consumption can offset the penalty for learning Supernatural Abilities for Gifted magical beings, even if for immortal magi the Arts and Supernatural Ability scores are almost surely so high that developing the related Virtue should be most effective way of learning a new Supernatural Ability anyway.
By the way, we finally have certain rules about what happens to abilities and powers linked to other realms when a mortal becomes a magical immortal: divine ones are lost, faerie ones become magical ones, and infernal ones become False magical ones. Stuff like Faerie Magic and Faerie powers continue to work, while Infernal Powers are upgraded to "mere" taint. Very nice. I assume the same rule woulf work if the mage would become a faerie.
From a cursory review, it appears that again, living-ghostdom is by far the most unappealing way of reaping immortality, while Daimonhood and alchemical immortality contest the prize for most effective method, according to what the magus would value, freedom of action on earth, or safety from destruction (although this judgement impinges on whether Daimons are able to send their Aspect to hunt vis for their advancement, or just to work on their earthly agenda, on their own initiative).
On this line of reasoning, I would point out that an alchemical immortal (or a magical beastie, for that matter) with a (durable) External Soul is almost as indestructible as a Daimon, since Warping is no longer an issue for it. I wonder whether having an external soul would free a Living Ghost from the Haunt survival requirement. I assume that it does, since it is just a powerful mystical binding.
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, rebuilding the Roman Empire, exploring beyond the known ends of Mythic Europe, completely rewriting magical theory, exploring the infinite depths of Arcadia or the Magic Realm, researching integration projects, etc., plus spending time on creating new items, spells, studying new Abilities, creating new Initiations, Breakthtoughs, etc. An immortal mage has plenty of suitably epic challenges before of him, and calls for his time, even if aging and warping no longer loom. After all, someone needs to do those pesky Hermetic Breakthroughs, sooner or later.
