If you want to use Venn diagrams then so be it:
The thing I can see is that --even with the best of intentions—the two guilds will grow separate over time. Members may join for one MMO but have no inclination to join the other. Perhaps a guild may have a rule that only their WoW members are allowed to join the TOR guild, but that will create a subgroup within the larger WoW guild that may eventually seek independence from the larger organization.
If both groups are large enough, does it make sense to maintain a single Vent/Mumble server or subdivide into two separate servers? If you’re recruiting for your TOR guild, is it really smart to just have a single section on your guild’s Forums for TOR, or should you create an independent website? (Or something in between?)
I’d imagine that the answers are a whole lot of “it depends”, but I’m curious as to how this little social experiment pans out.
(Side Note: I'm trying to track down the source of a potential issue with the blog. At least one blog reader has informed me that some browsers are showing some of the words without spacing between them. Instead of "this and that" they read "thisandthat" instead. If you see that issue, let me know so I have a better idea how to fix it.)