Maybe my players are just incredibly intelligent, but they picked up on the AP system and RoF pretty much immediately.
I'm terribly sorry to say it, but your argument in invalid.
your players can't be incredibly intelligent, as that would unavoidably turn them into GMs.
Pft, the nerve of some people...
Give them time, this is only their first TTRPG
I think the only major problem with RoF was the numbers, some weapons were way too slow to be worth using, but all it takes is a few house-ruled RoF increases and you've got a good system that's much more interesting and tactical than half/full/reaction.