We really don't burn much. We use it to supplement our heating system which is an air exchange with mini-split units. It works fine most of the time but needs help when temperatures get really cold outside. We typically fire up when temperatures drop into the 20s, which doesn't happen often in western Washington.Think about it this way. A replacement cat every 4-5 years will cost you about 1200$ if the stove runs 20 years and you burn a good bit. Are you saving enough more than that with a 25D eligible install?
If the tax credit were available, I'd go with the T5 even though it's a bit small for our home because we're just supplementing and could run it hot. Ideally the T6 would be offered in brown enamel and be eligible for the tax credit but neither is so. Ah, but for a perfect world.