I use Top Producer and I find it to make things more complicated. I'm currently looking into other solutions right now that are just more user friendly. It's not that Top Producer is difficult to use it's just a entire new project that you have to take time out of your day to learn.
The one thing about their e-mail system that I don't like at all is that it's not in real time. You have to keep refreshing it to get your e-mails. If you forget to refresh it you won't get your e-mails until you log in again. Not cool. . .