We have talked about it. The big roadblock is that the TT, unlike the TMF, has several add-ons which are incompatible with newer versions, and untangling that mess to upgrade is something which will take a lot of time. The second challenge is that the newer versions have their drawbacks. The search function in vB4 and 5 is widely considered terrible to broken, for example. We've been considering other forum software, but there is not much out there that is an improvement.