It just depends on whether you want brushed or brushless. Since you don't need all the power brushless provides, the only consideration at this point is price.

Be aware that sooner or later, you'll have to replace the brushed motor in the "standard" Sprint 2. If you do get the Flux, the power would have to be "detuned", or you will have to develop aVERY sensitive trigger finger. Another trick is installing a smaller pinion gear, to smooth out power delivery. Say, 18-20T.

For tires, go to raikoudrifttires.com and check out what they offer. I run all the types you will see there, and they pretty much cover every surface I run on. The prices are very reasonable, and I swear by them. Buying tires from HPI can cost a bundle in the long run, and they charge by the pair. Raikou charges by the set. You get three FULLsets of tires for the price you see at the website! Their compounds are better performers than PVC, in my opinion.

Let us know how it went!