I think that CBA should be eliminated altogether from roper. If you want the crate, you should be able to get it before or after attacking. If you wait until after, there's a risk you could fail and not reach it, or leave yourself in a crappy spot where you could possibly take fd. The crates should be a temptation, not a requirement... IMO. This would give people more time to knock and maximize damage and it would make getting crates more important than ever.
Honestly, I have a hard time trying to picture how would we could change roper to make it as luck-free as possible, but unless the crate issue is addressed, there's really not much else to talk about. That's why these days I've gotten kinda bored with ropers... whether I'm sober or stoned/drunk, luck does play a big part of the scheme, which is why I greatly prefer big rr these days because there's NO excuses.