Formidable vs. Gravity Forms

Is anyone here using Gravity Forms with WPMU products? If so, what's your experience?

I'm trying Formidable Pro (http://formidablepro.com) now but having multiple conflicts with the WPMU login redirect plugin and the Ultimate Facebook plugin. Specifically, these plugins cause Formidable to send notification emails twice.

Thanks in advance for any input you might have.

David