Here is a copy of the email I sent to a fellow collegue psd, hope it helps....
Hey ****...
Ok, I have dove the guardian... and the verdict is: I like it! the mask skirt is wider and softer, With an AGA I have some slight air leaks on one corner of my head... with the Guardian it was a nice secure fit with no air leaks. Also using the guardian and its super wide skirt I was actually able to pull the mask away from face a bit before the seal would break and air would leak and flood the mask, the aga would break the seal nearly immediately. Also the air space of the Oral/Nasal cavity seems smaller and thus the WOB (work of breath) is much easier, so it seems to breath easier... I thought the plastic buckles for the spider straps would be inadequate, however they were actually quite secure and are apparently designed to break before you rip the mask skirt so replacing a dollar buckle opposed to a 400 dollar aga skirt is probably money well spent. Overall I like the guardian better than the aga, It was softer in the skirt, had slightly better breathing characteristics, and has all the best features of the AGA (the Ambient breathing valve, nose block, and oral/nasal cavity) with improvement to some of the lesser qualities ( softer wider skirt to fit more faces and create a better seal, better breathability, and to administrators reduced initial cost and reduced annual rebuild costs) The only thing I havent tried is the comm system. But since it uses the OTS HotMic and ear pieces the same as the AGA I assume it works just as well. Any questions or want any pics of the mask just let me know...
Safe Diving
******