I'm happy to report better performance using my little smoker when firing it with lump. Today I smoked some mixed nuts and ran the cooker with Cowboy lump and some hickory, apple and mesquite mixed in for flavor. When I closed it up, I left one bottom vent open. Ten minutes later the lid thermometer was approaching 200 so I put the nuts in. The cooker then stayed over 200°F for about 5 hours with practically no fiddling. At about 1 1/2 hours in, I added a couple more chunks of smoking wood and knocked the ash off the coals. I did not put water in the bowl but we're getting plenty from the sky.
We're getting more than a drizzle. When the nuts were done, temperature was holding so I put some butternut squash in there to smoke that too. The temperature was falling off as that was finishing (deemed done enough, anyway.)
This is not spectacular performance compared to the bigger cookers but IMO entirely satisfactory in the 14.5 WSM. What I particularly like is that it held a reasonable smoking temperature with one bowl vent open for about 5 hours.