Yes, I've burned several bags of Nature's Energy from Lee Energy that I bought to test. The heat was reasonable but less than Hamer's or Prestologs. However, they were by far the dirtiest, most crumbly pellet I've ever burned and produced very large amounts of ash. I would not buy them again unless desperate. My dealer was completely out of pellets as they couldn't get shipments for a couple of weeks due to trucking co. issues, and they picked up some of these at a local HD for their showroom stoves. We were comparing notes on them and they had the same experience in multiple stoves. I'll burn the 3 bags I have left in my MVAE as it will eat almost anything, but then I'm done with them.
I also burned a few bags of Green Supreme earlier this season to test. A cool pellet with lots of ash, and also on the "not again" list. In fact, while I cannot comment about FSU's as I've never tried them I thought, "Your box store stocks primarily junk pellets, too." Then again, my HD did stock Prestologs for a few weeks, which were surprisingly good. I think their buyers will take anything labeled "wood pellet" if the price is right. And my local HD has been out of all pellets for over a week now, as they move in spring items. Will be curious to see if they restock at all. I do not depend on them!