Ilford's fill-agitate-dump method seems to work perfectly with or without HCA.
It appears that HCA allows one to get away with a less than proper wash, but it's unnecessary if one washes the film correctly ("correctly" meaning either the right number of fill-agitation-dump cycles, or the right number of minutes in running water).
Thanks for posting this. I've been using the Ilford method for some time, but never tested its efficiency. I'm happy to find out it works fine.