I've only done two projects, the second one is live for one more day but doesn't look to be able to fund.
Conversion rate on both has been about 10% (note that this includes those who converted before the 48 hours, so probably closer to 5-7% of whatever the total followers # was).
Not sure how other campaigns do with these though...
Wes W
FunDaMental Games
http://kck.st/2SVsUoH