posted 6 years ago
My personal opinion is that bells ("stratification benches") make less friction in the exhaust path, and may give more heat exchange surface, than ducting, so may be more reliable and less tricky to get right. Both rely on thermal mass, no difference between them there.
If you want most to warm your basement and plan to spend a lot of time there, a basement RMH is fine (though there are possible issues with draft in a basement installation). A J-tube style core needs frequent tending while firing (every 20-40 minutes), so you need to spend an hour or two or more depending on weather and other factors down there. If this is doable for you, that would work; if not, you would likely be better off with a batch box core which needs to be started, loaded, and fires by itself for an hour.