This looks like a great plugin, but it's just a little short on the "free" features like only giving you the option for a "fade" transition.
I use a plugin called s2Member for my membership stuff - it is completely free and PACKED with features. And they have two levels of paid versions as well. I would almost surely never need the paid version, but I upgraded to the highest level possible simply because they offered so much value at the free level, and they have an active community. THIS is the spirit of WordPress development.
There is such a move afoot to offer "just barely enough" -- then if you want decent features - pay or forget it.
Don't mean anything disparaging here - like I said, I'm sure it's a great plugin, but I'll never know because there's just not enough to really take it around the block.
Back to the ol' standbys. :)