I got a Harman pellet stove in December.  I've cleaned it three times since then.  Not a big deal, takes about 20 minutes or so.  I've gone through 2 tons since than to heat a 2,000 square foot house.  It is more than I thought I'd go through, but, its taken some time to get the thermostat set where I want it and the fans set up right to circulate.  As far as the cleaning thing, I got a ton of pellets from Tractor Supply that produced a LOT more ash than the ones that I got from the company I bought the stove from.  Their pellets produced way less ash and I bet I could have gotten a lot closer to a ton of pellets before cleaning (maybe 3/4 of a ton).  But, as the soot/ash builds up in the stove it does become less efficient, so, I've cleaned it more often simply because I had the time on a Sunday morning to to it.  I do like it and it certainly is cheaper than heating oil.  Of course that comes with a price: your time to load it and to clean it out.