I can't actually think of an easier system for beginners than BRP. You can play CoC already, so basically you're playing BRP - there is no real difference. As Rurik said, a percentile based system seems to be "common sense" at first glance. It's intuitive, and once learned, it's damn hard to forget!
Opposed Rolls are a storm in a teacup. Have a look at what's written in the rules, you'll feel a lot better
Some people are resistant to the idea cos it changes the way they've normally played BRP - to which I'd say, play exactly however you want to, it's just a game! For me, they're simple, elegant, flexible, obviously optional, and add a nice tactical touch to parts of the core game mechanic.
I certainly wouldn't judge how simple the system is from this forum! Most of us here are grognards fussing over minutiae, not a representative section of opinion at all!
Is there a downside to BRP? I'd say if there is, it's the fact that it lends itself to many different styles of play, and people seem to love developing houserules here and there, which if you try and puzzle your way through them can seem bewilderingly obtuse at times (as you've noticed
). Some people may hoard experience rolls like gold, others might dish them out liberally, some may make magic low power and scarce, others may dash around tooled up to the eye-teeth like Terminator. There is certainly no One True Way to play BRP, so you do have to be able to accept other people doing things very differently - but to be honest, that's only if you participate in a forum like this.
Other than that, honestly, I can't think of anything wrong with the system; on the contrary, I think it's the best system on the market. It wouldn't have kept my enthusiasm and interest for close on 30 years otherwise!
Cheers,
Sarah