I've sold a lot of heatmaster with hardly any issues at all. The design of the ml series and e series with heatmaster is very similar, only with heatmaster your gonna save a considerable amount of money, and get stainless steel construction. I really like the shaker grates as well. I think p and m is a good stove as well but there cost make it impossible for me to sell them here in my market.
Heatmaster truly goes out of the way to help folks keep there warranty in tact, with all other companies, once you leave your dealer, they don't care if you ever send in a water sample and for the most part hope you forget because that lessens the companies liability, with heatmaster they provide you with your first gallon of treatment, give you 4 shipping containers with bottles, shipping labels, u name it. Also every year they'll send you an email/post card reminder telling you it's time for a water sample instead of hoping you forget. Heatmaster water testing is also free for the lift of the stove.
If you'd like to talk more in depth, feel free to call me, by carrying more than one brand of stove it really helps me provide good feedback to customers. For example, if your a p and m dealer, all your gonna say is oh well there the best blah blah blah, if your only a central dealer, u know same thing, when folks show up here they don't here a one sided this is the best sales pitch, I take the time to show the pros n cons of each brand/model.