Yes, it's true about the 6.5. Much better option.
As for pinions, if you use all SCTE stuff for the conversion, no, your pinions won't work. SCTE uses a mod 1 spur. The SC10 4x4 can use 48p or 32p. Most use 32p. If you want to use 32p, you can buy this spur:
http://www.rc-monster.com/proddetail...rod=rcm10tspur you can use 32p pinions with that.