The Cheyenne IIXL is the better of the smaller Cheyennes and it doesn't have the SAS systems, it also has an improved environmental system over the I and straight II. Parts are not a majot issue, if you get stuck Cheyenne Air Center are a great help. The autopilot can be a bit of a problem but there are still people around that look after the KFC300.
Speak to AirMed at Oxford as they have a good mix of IIXL's and IIIA's or PM me.