rcmike,
I ran a jammin pro all last year and broke one front cv in an encounter with a pit wall at the top end of a 120' straight away. Also lost in that encounter was an A-arm, king pin, hinge pin and a shock shaft. Other than that one incident I broke a stone guard all year. I have also built and raced a SP2 and a ProSpec and can say that I felt the quality of parts was higher in the Mugen kit, followed by the Jammin then the SP2. That is just my perception without any scientific basis. A Crowd Pleazer 2.0 for a MBX 5 fits very well with minimal trimming. However, I just heard that they make a CP specifically for the Jammin buggy now. If you decide to go for something else, I felt that the ProSpec was a VERY stable buggy but it didn't turn nearly as hard as the Jammin or the SP2. They did come out with new set of lower arms and pivot blocks that are supposed to help that. Now for a shameless plug, I have a Prospec with 3/4 of a gallon on the chassis for sale (so little use because I liked my jammin better) with a few spares and 2 nice bodies for $400.
Scott