Would you believe I've had a LBGE for a couple years and only just got around to using it for hamburgers? These were left-over frozen home made ones (from store ground meat). I got it stable at about 400F tossed in a few pieces of hickory, and gave them about 7min per side. It beat the frying pan method, because the burgers weren't sitting in their drying up juices the whole time and no pan to clean.
I even used a mix of Publix Greenwise and Best of the West Mesquite lump (which I hated on its own for steaks) and the burgers came out ok.