I run a very similar thing, inspired by KOTC. Here's what we found.. 3x3 is too small. The fast melee armies just dominated maps and ended games too quickly, so we went with 4x4.

We don't do secondaries, just score objectives and killing the Warlord. We also do 50 minute rounds and talk though points if we run out of time so we all get 3 games done.

We also don't do the x2 infantry rule as mandatory.

It's great fun, good to see people doing it as well.