Just being curious, what were those?
Briefly, since I don't really want to pollute another forum with our difficulties:
1) Resource issues. 4GB of ram, 60GB of disk, and 4 processor cores struggled badly with about 250 regularly posting users.
2) We sorta... "fell out" with the developers and they told us, in no uncertain terms, to go find other software. I, along with most of the others on said forum, are currently banned on their main forum for another 250 years or so.
PM if you need/want to know more.