I just recently dived into the Beta of MC12 after "Sitting on the fence" for a while, as it seemed to me that it was a bit "flakey".
I would not go back to MC11 now. MC12 is quite mature even though it is still a Beta. It handles my library of just over 40000 audio files with ease.
Why not take advantage of the cheaper upgrade p;rice and splash out? You won't be sorry!
I also run library server for three other home PCs (wife's office, lounge, and laptop with floats around - ie. out next to swimming pool), and it works very nicely indeed.
Go on! Take the plunge; enter the world of 12