I have had a few questions regarding the differences between WhoIsIt and Ringleader, so I thought I should answer them here...
Basically, I designed Ringleader to provide the ability to have different "sound profile" settings for your applications. The purpose would be to assign certain appropriate ringtones / volume settings for different situations such as work, school, etc. Ringleader also provides a way to manage all of your application ringtones through one central screen. That is the basic functionality of Ringleader.
WhoIsIt on the other hand was designed to setup custom contact ringtones for phone calls, Gmail, SMS, and MMS. It also includes the ability to setup VIP contacts and adjust your volume and vibration settings within each profile (just like Ringleader).
The only thing that the two applications really have in common is the ability to setup profiles and control the volume and vibration settings for your phone.
I added the ability within WhoIsIt to switch your Ringleader profile when you switch your WhoIsIt profile. I did this to help any Ringleader users out there so that they did not need to adjust there WhoIsIt profile and then adjust their Ringleader profile. I just gave them the ability to automate things if they decide they need to do so.
I hope that helps explain the differences between Ringleader and WhoIsIt a bit better.