I've been using both. When I first started using my offset, I was able to run @ 240-250 no problem. I seem to have trouble keeping it below 290-300 lately, using RO briquettes mostly, but a mix of both. WallyWorld almost always has the RO lump in stock, and it looks like K usually has the 18# briquettes in stock. Lots less ash than "THE OTHER STUFF". Lots less.