I am not big fans of WPMU/Inscub either. I bought Sociable Pro plugin about a year ago from them with the intent of geting paid support from the author. The author was letting them proces the transactions but he wasn't responding to anyone on their support forum for it.

I asked WPMU several times for help and they said basically tough luck and didn't want to offer me a refund even though they took my money. After countless emails they didn't respond to me. I finally got PayPal to refund my money. Horrible customer service.