After pondering this thread, my resolve was to just give everyone 3 primes (4 for humans) and change the 18 target for non-primes to 15... which is mathematically very similar to your approach, Talysian.

I'm skipping the secondary attributes (which I actually much prefer using, BTW) just because they're not easy to assign in the FG ruleset. At some point I'll either add another column of checkboxes to support Secondary stats, or make the existing column a tri-state check box to allow for choosing either primes or Secondaries. In the mean time, I have too many other things to pour my time into - I'm *still* trying to get that Old West game (based on C&C, btw) off the ground... almost there!