It works reliably on this php version (Had to make a few edits to get it to run on PHP5). If i think of anything else i'll let you know.
EDIT: Anyone who wants to see the ACP Controls for the Download system i'm willing to let have a look, but i will only grant Admin Access to those i know will not screw with ANY of the settings.
No problem for us if we ever install anything, we use PHP 4.3 here.
You should install a test board for ppl to muck with in the ACP without worry.
I do like the idea of some of these mods, however one thing to watch for: Do they introduce any security holes into the system?
Many mods I have seen have very sloppy code in them and it wouldn't surprise me if there are unchecked vars and whatnot in them. (Which could let people inject SQL or other nasties into the system, what could happen is obvious).
the IBStore is one such mod I'd like to clean up before installing. (It's quite sloppy)