5,110 lbs = 2300kg - bad news on that front. A Jetprop Malibu conversion will probably be cheaper to fly. Mind you, somebody who wants a jet will buy a jet no matter what, IMHO.
Diamond has a bit of a history in keeping their numbers down, their aircraft tend to perform better then published
Not sure I would agree. Look at the DA42. They talked various figures e.g. 210kt, +700fpm SE climb rate. None of these were achieved, not by a long way.