Avoid ash pans. Even if you like the convenience, the bottom of the firebox is a terrible spot to have an air leak, and a likely one too. Bad idea all around. Search the forum for threads where people have melted the insides of their stoves by accidentally (and sometimes intentionally) letting air in right underneath the fire.
I've run four different stoves with ash pans. The worst leak I've had was in the Buck 91 where the gasket was mounted on the front of the pan, and it relied on a spring-steel strip to hold the pan and gasket tight to the housing. I got the stove used, and by observing the burn, I quickly saw that the coals were glowing over the ash dump. I replaced the gasket, which had frayed a bit where the ends of the gasket came together. Even though it leaked there, I'm pretty sure I was nowhere near damaging the stove; There is always a bit of ash around where the air comes in, insulating the area around the dump from coal heat. Maybe it would be more of a potential problem on a BK, with their thin steel construction. The Buck hinged-lid system is far superior to fumbling with the plug and the dinky ash hole in a BK.
The Buck system, with a large ash dump opening and a hinged lid, was the best non-grated system I saw. The opening was in the left side of the floor, so it was easy to sweep the coals to the right side, open the ash dump lid, and sweep the ash into the hole. The T5 isn't too bad. The lid hinges downward, and you can put a stick under the lever to hold the lid open while you work. The hole isn't very big. And you have to make sure the lid is locked into the closed position when you're done. Beats a plug, though.
I don't recall if you ran any other stoves before the BK, but if you've never had the best ash-handling system, with a grate in the floor, you don't know what you're missing. As soon as I replace the old Englander 84, which I had to shovel out, with the Dutchwest and the grate, I knew I never wanted to go back to shoveling, trying to contain dust, and having to immediately take out a hot pan of hot ash and coals. I briefly ran the Woodstock Fireview for more heat output, but ended up fixing some air leaks in the house to where the grated Keystone could keep up more easily when it got cold out. I just run a poker through the ashes to drop them through the grate into the pan. Repeat that five-second job, until it's time to slide the barely-warm pan out and dump it after a couple weeks.

BTW, I've never replaced the ash door gasket, and I've had the stove ten years.
The BKs can hold a good bit of ash, but eventually you have to deal with it. Have fun. As for me, I'll avoid your advice to avoid the ash pan.
