I have dived an ARC mask, and we are an Atomic dealer - have always used toothpaste and nothing else to clean the lens - in fact, it says that toothpaste is acceptable on the tag that comes with the mask... The ARC coating is extremely durable and will last many many years of regular use...
I never ever use defog, instead, I use toothpaste twice upon opening a new Atomic mask, and then once a week... I spit and scrub right before submerging, and I NEVER have had an Atomic mask fog up on me (except when it was brand new and I hadn't scrubbed it twice yet)...
I would never use softscrub on any mask - that stuff is like sandpaper and although may be very easy to clean a mask, I feel like it probably leaves tiny micro scratches in the glass...
PS - I use toothpaste on both the inside and the outside of the lenses on the Atomics - if I don't I can see where the warning sticker came off (out of the water), and also tiny bubbles will stick to the mask lens...