Over the last few years I've "looked" at several different pellet stoves.
All of them had the ability to adjust the btu output.
Some of them had two augers, some dropped the pellets into the fire pot from above and there were a few that "pushed" the pellets into the fire pot (this type is suppose to push the ash up over and out of the fire pot). I've seen a few demo's (county fairs and such). I was VERY surprised at the amount of heat being sent outside.
Over the last few years I've seen the prices go up and the quality... not.
My "opinion" is the heat chamber (what the fire pot sits inside of) are too small.
Not enough area for heat exchangers, remember that "high forced draft" that's needed.
I've talked to a few pellet stove owners, the number one issue they had/have is that the "fire goes out sometimes"
Another "opinion" of mine is their taking heat away to "early".
Ever burn wood in a wood stove thats had it's fire brick removed?
An auger feed system tends to "jam". it's the nature of the beast. However if one spends any time working out the "details" of the "transition" point. Where your trying to push pellets (or woodchips) into a small tube/hole and prevent any air flow from the same). I don't know how one would do this with an chain or a conveyor belt.
A properly designed "volumetric" (I'm not real keen on bixbys term "fairies wheel) system is another "proven" method.
The comment about pre-grinding the woodchips is very good idea as long as you don't spend a lot of money/time doing it. course, same is true with making wood chips. If their FREE.. that's something else!
in the end.. it's gotta be safe. can you sell it to your insurance company?
I've thought an outdoor biomass/boiler. (no pressure in the boiler)
Don't let the family sing to you.. "burnin down the house"
and have fun!