Terrible company to deal with! They kept billing me even though they weren't supposed to. When I called to ask about it hoping they would refund me at least some of the money... not only did they not do it but they were VERY rude to me on the phone. The manager actually hung up on me and I wasn't even being loud, rude or anything to her.
I've also heard that they are a nightmare to deal with from a merchant's standpoint as well. I would steer far clear from them if you are thinking about using them for your business and I certainly wouldn't sign any agreement with a company that is using Member Solutions. It's likely you may end up screwed like me.