Sure, wrong guesses are just as welcome here.
If it's using two Faital Pro rated at 600w each and a 1,000w 15 I'd guess that's where he got the rating. If it performs similarly to the other Tanks I wouldn't want to be around hitting it with 1,000w watts.
I was shocked at the amount of power I found I could push my Tank 1012 with. You'd probably guess that I couldn't. And like most folks, maximum output isn't the point. I played outdoors Saturday night with minimal FOH and the sound engineer, out of the blue, told me I had one of the top three live bass tones he'd ever heard. Cut through effortlessly in the mix. I had the Master on the Quilter at 160w.