Are you guys not considering a top of the line F2000?
That is a fantastic airplane.
Everything NowCorp said about the 900 I can second. As is the case for most TFE powered aircraft, the 900 is very ISA sensitive... but so is the 604/605 for that matter.
However... from a back-of-the-airplane perspective... nothing in that range beats the 605's cabin.
If you can't go as big as a G450 or a F2000, then I think you are in a toss-up between the two.