Still, the reason why i say this is because it might be confusing to people, they might think that they can't use a theme with a lower wiiflow rev. number..
It was also like that already in the past. But i get your logic too.
In view of the permanent changes, I can assure you that the themes are not backward compatible.
This is not always the case, about twenty revisions, they will, but only for a single revision that is no longer possible.
To avoid any confusion, I will give the WIP links themes only on IRC.
After all, this topic is a WiiFlow topic, not a WiiFlow-mod topic ... whatever ...