Ah, wonderful to get closure on this, and thanks for submitting the fix! I had trawled the mailing list for netatalk but didn't think to check the git repository.

Out of curiosity, do you have any thoughts on 7.6.x clients and large (> 2gig) shares? I know it somewhat depends on both of OS/Finder versions and the AppleShare Client version... and as I mentioned upthread the "volsizelimit" seems to have been restricted to Time Machine shares only, otherwise it would have been a nice way to handle this.