Hawke, we (furfly) have built a couple of sites based on ACS 4.2 Tcl and I can confirm the comments here that it was never quite ready for prime time. We've done a lot of bugfixing along the way, but there is still more to do (if these were exceptionally busy sites I think we would be seeing more problems than we are). If I were in your shoes I believe I would try OpenACS; you might still have to do bugfixing but at least there is a community to contribute them back to, which is not really the case any longer at aD.
