Lump burns hotter, Longer. You can get unstable temps from briquettes or lump if your not using it properly. Here we go again. It's the pit master, Not the pit that puts out good barbecue. Any thing is easy if you know how. The difference in lump and briquettes is night and day. Can I get gravy on that?
Actually I've been using lump for my longer cooks. I'm sure there's someone out there with a different opinion but I've found, when I maintain the same pit temperature, I get about 2 to 5 hours more out of a filled ring (WSM) of Royal Oak than I get from a filled ring of Kingsford. (Side benefit is less ash) I use them both.
If asked to speculate I'd suggest maybe the higher combustion temperature of the lump requires less fuel to be consumed in order to produce the same amount of heat. But I'll leave any further discussion to the engineers out there.
Here's my 2 cents. :rant: I only use charcoal as a starter. Normally I put about 1/3 of a bag in the firebox, light it up and once it's hot put on the wood. I cook entirely with wood once the fire is going. I've always used Kingsford briquets and got an even temp fire, not hot, but steady and long. When I used Royal Oak, the briquets take longer to light, longer to get hot and burn low and slow. I don't care for Royal Oak briquets at all. But, I've been reading so much about the lump that last weekend I used it to start the fire. It was Royal Oak lump. I have read several reviews on this one, and it is not rated that high either. The Royal Oak lump started quickly, much faster than the Kingsford briquets, got hotter quicker, but did not last as long, as Kingsford briquets. You see both brands bring used by comp teams all time. Isn't it the Weber Grill that uses Kingsford exclusively in the resturants? My choice in the future? I'm buying a weed burner to start my wood and swearing off charcoal for good. But if I need one, I will probably buy Kingsford. :pickme: I like the slow and even temps.