This is a long time coming, but I wanted to wait until I had the ABV and a good amount of dives with the Spectrum before I gave my impressions on it. Long story short, its an incredible mask, and the minor issues I had with it were a result of user error. I know there aren't a ton of reviews out there, so hopefully mine will help people with the decision. I have completed over 40 dives with the mask and here are my impressions:
The first few times I used it, the lower lip of the mask kept slipping out from under my chin. Once I got used to the fit, I adjusted the straps and stopped having that problem. On a few dives, the mask would also shudder when I breathed or moved suddenly. I tuned the breathing on my regulator, and the issue stopped completely. The mask seals really well, and after following the directions from OTS to break in and treat the mask, I have never had a problem with fogging either. It keeps your face warm during cold water dives, and the ability to equalize without a nose block, while still retaining a full-face mask capability is amazing. The ABV really helps save on gas during long surface swims, and will not take in water into your mask even if you are 1-2 feet underwater.
Only recommendations I have is to get a QD attachment for your regulator, because zip tying it into your mask can be a real pain. Right now I have a single SP G260 attached to it, and I only plan on taking it off for maintenance and an occasional deep clean. I would also highly recommend that you practice donning and doffing the mask, and switching to your secondary/octo if something goes wrong. It also wouldnt hurt to carry a pair of goggles or a secondary mask just in case.
I love my Spectrum, and it will be really hard to ever dive with a normal mask again. Is it necessary for most divers? Nope. Is it a real nice mask to have if you have the funds? Absolutely.