A .75 - .90 size fast sport airplane like the Patriot XL (by Great Planes) or one of the .75 - .90 size pusher BobCat 'knock-offs' are very good planes to fly before getting into jets. These planes will also expose you to retracts and flaps which are found in nearly all jets.
As far as the Reaction 54 ..... it is a great trainer and a great flying airplane in general .... even as a sport plane beyond training (I have one). The only drawback to the R54 is that you have to build it ... and there is a good amount of work involved. As mentioned earlier .... I think the Boomer is a wise choice for a first jet. Bob