I did try the membership plug from wpmu and it got on my nerves. The learning curve is WAaaaaYYYY!!! to big and it takes forever to make it work. Also the costumer support Is really bad, specially if you live in the US. The hour differentials are way to extreme and if you need “fast help”, believe me, you won`t get it.
I did got my full refund and use the money to buy some books to see if I could build my own plugs.
I`ll be trying the s2members today, I`ll get back with my results.