Don't discount the C421 on the basis of the wing spar SID. It makes for a very good bargaining tool when negotiating the purchase price. The mandatory inspection is very expensive in the UK but there are other JAR approved maintenance organisations in Europe that can carry it out for a fraction of the price. I'll happily let you have the details if you want them.
It's certainly a better aircraft than Navajo/Chieften, a cabin that's a lot quieter than a King Air cabin and when you do need to replace the engines - alot cheaper than the King Air donkeys. And when the diesel engines are approved, well......