I use JV Manager 2 (Fantasos) and it does pretty much everything you
would want it to do. I also own Butterfly Marketing script and yes it's a nice
script that I have used before, but don't like the fact that I need a new installation
for every new site I create.

With Fantasos you only need one installation for all your sites. Plus you can do so much
more like coupons, credit points, run resellers programs, and more.

I highly recommend Fantasos