Originally Posted by IO540
though under FAA a TR is mandatory only if above 12500lb.
As slim says - there is no weight mentioned. That's because ALL jets need a TR, the 12,500lb minimum limit only being applicable to pistons and turboprops.
Insurance requirement can be a big issue; in fact the great majority of light jets are not flown by the owner.
The insurance company will probably insist on training from a recognised provider such as Flight Safety or Simcom before they'll even touch you.