So the bottom line is that with XY configured to show 64-bit shell extensions, it's functionally equivalent to a 64-bit file manager as far as I know. Doing a ton of work to make it a true 64-bit application would be a compete waste of effort for no gain other than to be able to say "XY is a 64-bit app".
And to waste Don's efforts on that would be a shame.
-mwb1100
As far as I know XY is written in VB6, which means it won't be 64-bit or multi-threaded. But as long as it works for people, and Microsoft continues to support running VB6 apps (which they do at least for the lifetime of Windows 8 ), there should be little problems.
At some point WoW64 will probably be phased out (when we are all on 128-bit processors), just like WOW was removed from 64-bit Windows, but that's further into the future, so as long as you don't need a file manager on something like WinPE 64-bit, that's not a real concern right now either.
Personally, I think the lack of multi-threading is a lot worse than being 32-bit, if you want to worry about something.