I'm not sure why anyone would prefer an original MPU to an Alltek. I haven't noticed any differences in gameplay, but maybe I'm missing something. Most of the aftermarket boards have nice design improvements too.

I prefer a really nice original playfield to a repro, but nice originals are hard to find and usually have a price premium. My tolerance for playfield defects goes up with the age of the game. I have a Skateball with several areas worn to the wood, and I found after a few months that I just don't care. It's playing really well, and it looks natural.

Replacement part quality varies a lot, but I've been very happy with CPR playfields and plastics, Pinball Inc ramps and Planetary's cab decals with "next gen" printing. On the other side of the quality spectrum are insert decals and drop targets. Backglasses vary from excellent to terrible, but I think that's getting better too.