I think he meant that updating Arc didn't make any difference to the requirements, not that using an old mzscheme doesn't make any difference, which it certainly does. I wouldn't be using Arc if there hadn't been a patch to get it working on newer mzschemes; the git "wiki" (http://git.nex-3.com/arc-wiki.git) works on said mzschemes right now. It may not be official, but it might help scratch your itch.
