A recent posting to the EVN addons page contains this sentence:
...This plug-in is in .rez format, so it is for Windows only.
While that statement is correct in and of itself, it implies that the plug referred to can not be used on a Mac at all, which is not true. David Arthur has created the "MacPluginConvertor101" application, available on the Utilities addons page, which converts .rez plugs into Mac resource plugs.
So Windows developers, yes it's a good idea to warn folks about the format of your new plug, but statements like the one above will very likely scare off unknowledgable Mac users and you won't get as many downloads as you possibly could. You should put something like this in your addons description instead:
...This plug-in is in Windows .rez format, so Mac users will have to convert using MacPluginConvertor101.
That way everybody is made aware of what they're dealing with and more people will benefit from the efforts you made to create your new plug.