It's possible to do this with no ill effects save that teh frist beer or 3 have an unusually high trub content. It's really not that difficult, especially if you make sure that you are completely fermented out before you transfer.
The one thing I HAVE had trobule with in this space is the presence of hops (even pellet mush) in the trub (or dry hopping in the keg). I'vve had hopps plug up the poppet so bad that the beer comes out in a trickle. It's easily solved but it involved depressurization of the keg and removal and cleaning of the poppet while the beer is in the keg. Defintely a PITA.