I'm pretty sure when most people say they have the House of Thule client they really mean they have Underfoot if you use the identification method described here:
http://www.eqemulator.net/wiki/wikka...ClientVersions
I know that when I hail one of the NPCs on the Funhouse server it says I have House of Thule even though I am 100% certain I have Underfoot. It could just be mislabeled and I believe that may be where the confusion is coming from.