In our sagas magi rarely use arcane experimentation, because in our experience the benefit is almost never worth the risks. So, despite a long play history, the following questions have never come up so far.
If the effect you are experimenting on comes out modified, do the modifications count against its level/Arts? An example given in the book (side effect/major side benefit) is a spell to transforms you into a wolf that, as a result of experimentation, also allows you to speak to all beasts while a wolf. Does this add an Intellego requisite? Another example given in the book (modified effect) is a spell that comes out with an increased range, or duration (say, a D:Sun becomes D:Moon). Does this add a magnitude to the final spell?
If you work from the lab text of someone who had experimented and obtained a side effect or modified effect, is that your starting point (i.e. even without experimenting yourself, in the example above you get the wolf-that-speaks-with-all-beasts effect)? Or is your starting point the baseline from which the experimenter worked (i.e. if you do not experiment yourself, in the example above you only gain the wolf transformation without beast speech)?
If the answer to 2 is that you start from the already modified effect, what if you experiment yourself and gain a side/modified effect? Do results stack?