I'm sure you're right about stability and the issue about parts, Piper didn't build many Cheyenne airframes, expecially not the 400LS, while there are several thousand Beeches flying and they're still in production. I was mainly interested in the performance available from TPs. My personal favorie is the Piaggio, but that's because I think it looks pretty cool and appears to go like stink. It may be a dog though, I don't know...
The PC12 and TBMs have impressive performance also except for the purchase price. And they can't be used for commercial ops as pointed out.
A piston twin sounds like the obvious choice after all. I asked this question in another post, but would a modern light-medium piston twin have any chance in todays market? Or would it be impossible to build one that could compete costwise with old refurbished hardware? The Adam A500 looks a bit disappointing to me. It seems to offer little improvement over anything old and used and costs a fortune...