Re; longevity, Mark Evenson, in the past, has talked about the 2stone basically being immortal, but I'm not sure I go that far in describing it. It's got a lot of stainless steel, which is definitely going to prolong it's life much further than the blackstone, but it isn't 100% stainless. While we haven't seen a blackstone rust out yet, I think it's pretty clear that 2stones are built to last longer. With the coupon, the 2stone is still 3 times the cost of a BS. Is greater longevity worth 3 times the price? I think, until we actually see the BS start failing, it's too early to determine value from a longevity perspective.
Besides, Blackstone is offering parts at seemingly very reasonable rates, so even if a component does rust out, you can just replace it. If, say, the heat shield is prone to failure and costs, say, $30 to replace, you could buy a boatload of heat shields before you'd be anywhere near the cost of a 2stone.
You can't compare two ovens without comparing the pizzas they make, and, so far, the 2stone has produced some amazing looking pies, but I don't think any have been of a Dylan caliber.