The SPS tactical have a 1:12 twist (.308) I heard that it's not the optimal twist for heavy bullets, is that true or just bulls**t??? The Savage 10FP, 10FCP-K, etc... comes with a 1:10 twist.

10 inch twists are WAYYYYYYYYYY more than you need for a 308. a 1:12 twist will stabilize any bullet you can stand to fire out of a .308 winchester cartridge. 14" twists will stabilize any 156 grain palma bullet going and they are LONG (It aint about the weight, it's the length!)
If you were building a 300 RUM and wanting to shoot 240 Sierra's YES, get a 10 inch twist
There are down-sides to over spinning bullets. This fascination with 10" twists in 308's baffles me.