Hehe, i surely hope not, but if they can i want that power o.o possession is always fun :D
what i was refering to mainly tho in regards to the affects, was that do the good choises and maybe it won't affect you at all, maybe you learn a power that can actually be usefull for a goodsider, if opt toward the evil side, you might be a small bost to your darkside and learn a power benefitting a darksider
Basicly, a LS jedi would turn the tables in a manner of speaking and learn something unexpected (you can often learn surprising things from an enemy without them having belived it possible)