I moved my MSN group to Aimoo and Multiply.
Multiply sucks. It has the same outdated format as MSN and the transfer looks like a jumbled mess.
I found Aimoo does a nice job. They archive your MSN sites whole history, plus gives you modern features like a fully functional chat room and the ability to do alot of high end graphics with html and javascript. Very crisp looking sites. You can add music, video, scrolling banners plus lots of other nice functions.
Managers have total control at Aimoo on who gets into the groups.
Going to Yahoo would be like going back in time.