Are there folks here using the RoundTrip plug in order to prepare for itunes uploads?
I'm hearing they can use it in Protools with some emulator or other device?

It's an Apple product, so of course it's AU-only. The good news is you don't need it.
 
If you want your master to be "iTunes-ready", or for that matter MP3-ready or AAC-ready or whatever, just set your limiter's brickwall to -1dB. Or use a limiter that detects and/or prevents ISPs, such as Ozone or Pro-L. If you need confirmation, convert it into the lossy format of your choice and load it into any audio editor that reports overs. 

Excellent thanks BF. I use Audacity for overs after using the stand alone AAMS for mastering my Sonar WAV exports.