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A 500 sf cabin should be easy to heat with a 6" RMH, but there are a couple of questionable factors in your proposal. First, a basement is not a convenient place to put a standard J-tube RMH, as you need to keep an eye on it and tend it every 5-20 minutes depending on the particulars of your installation. Remembering to go downstairs that frequently will become a chore and a distraction from daily life. A basement location is also problematic from a draft standpoint, as the house may have a stronger natural draft than the RMH chimney, and cause smokeback. Lastly, do you really want this "potato cellar" to be the hottest part of the house?
A "sealed draft" system that exhausts through the wall will not naturally have a strong draft, and might even draw smoke back inside through cracks in certain wind conditions. For the best, most reliable draft, you want the chimney to rise through the middle of the house and exit at the peak of the roof. This more than anything will ensure a good draft in cool/cold weather. Depending on a sealed draft system when you will have to open the system regularly for feeding fuel is bound to fail at least occasionally. Better to ensure good draft with a good chimney, airflow paths and system element design, possibly including a startup bypass to reduce drag during cold starts.
http://www.woodheat.org/the-outdoor-air-myth-exposed.html
The firebrick heat riser and combustion core will be the most durable available design, with the price of slightly lower efficiency than cast refractory cement core and riser. If you want the best efficiency, research the good info here and on the donkey32.proboards.com forums on casting the core and riser. If you are uncertain of your skill at masonry and fabrication, you may be best off building an all-firebrick core, which can be taken apart and rebuilt several times if you make a mistake the first time.
Beware of youtube videos, there is excellent information, but also a ton of bad examples. Be especially wary of any build that uses metal as an essential internal component of the combustion core (feed tube, burn tunnel and heat riser), as these will fail quickly. On the other hand, metal duct used as a sacrificial inner form is perfectly acceptable, as long as the design includes refractory material that can stand up to use after the liner burns out.