Not really an "advantage"; however, the fact that it's written by the same guys that wrote cgminer (and BMminer being a bastardized version of it) , would suggest that the connection code from proxy to miner would have to be as good as it gets in ckproxy. That's not to say that one is "better" than the other, just that that ckproxy/ckpool can't be "bad" at handling the connections.
Can't argue with your logic. In any case I have thoroughly tested stratehm with S7/S9 and zpool and it is significantly more stable having a stratum handling failover as opposed to connecting cgminer/bmminer directly. It's far from perfect, but I know crackfoo is still trying to get the sha256 stratums more stable which, with either method, could potentially solve all the problems.