I see ads for these new manufactured firewood blocks everywhere. They are made from hardwood waste and have no glue/binders. I dont think I'd ever 'switch' to using them full time( I hate paying $$ for something that I can get for "sweat equity'). But I'm painfully curious if they burn as hot/long/clean as advertised. Has anybody used them? The ones Ive been seeing on my local CL are called 'Envi 8' , but they are made by several co.'s. Anyone have a report?