With your current chassis set up I would buy into a big twin and not a tripple. A tripple is fun to ride if you have a chassis that can take the power output and hangin the hell on. I had a 8mil tripple T-rex and it was a handful in a ridged chassis for the 100 yrds. My 610 cheetha is more user freindly running the 100 yards and for the time slip difference I would say spend your money on a twin.
Repair bills are costly also on a tripple vs a twin. There are too many one off parts on a tripple that you can't just run down to your local dealer and get.
If your really serious about buying a tripple then I would buy one that is complete bike ready to go not just a motor. Hope this will help.
Thanks
505