Taylor, just a suggestion regarding your XT builds. You may want to consider including a brief txt file with them, identifying what feature, bugfix, or tweak you're attempting to test out. That way, those of us who KNOW where to find them but aren't necessarily told about them, can test them out and provide feedback regarding the changes made.
The features and tweaks are pretty much all by request. In other words, for specific people or mods. So, really, the person who requested the feature is the one that tests it out. It also means that most/all of the features are generally secret and only a select few people are meant to know about them.
DaBrain is really the only person that is aware of all of the changes in the build, and that's mainly because he requested or otherwise initiated them. Most of the tweaks have been made specifically to address concerns expressed by DaBrain and Vasudan Admiral. These are things like bugs in multi-pass blending, problems with envmap and/or specmap blending, lighting issues, memory usage issues, texture filtering changes, etc. Changes to the lab come from ideas expressed by numerous people, including myself, but there is nothing really secret about that, since it's pretty much all in-your-face stuff.
That's really the point of the Xt builds though, to test out a LOT of features that exist in a state of flux. One build to the next could see anything from a small tweak, to a complete rewrite of a feature. Getting too much input actually hurts the process, which is why only those people directly involved with the development of that particular feature know about it. Once things stabilize they will be included with more stable/finalized builds for everyone to test with and find any remaining bugs. And since most of the new feature changes deal with new content, that also gives the artists and mod/model makers plenty time to get their new data ready for testing as well.