Both of my drums will run an easy 20 plus hours with the large charcoal basket. Now that's loading it with about 12 to 15 lbs of lump.
I did make the first one where the bottom comes off for cleaning but in reality its more of a pain in the behind then anything. Lump has so little ash that with a pizza pan or similar in the bottom, the clean out is no problem. The only time I get grease in the bottom is when I have it loaded to the gills and the drippings miss the fire basket.
The key to the drums working so good is the strict control of air flow. Having a door is yet another place for the air to leak in. In My Opinion.
A couple weeks ago I cook a PR and a brisket, brother in law wanted nothing at all on it just bare brisket. The PR got salt and pepper. Both turned out fantastic, not dry at all. I don't think this would have been the case in a different style cooker.
I credit the drum for a great turn of food.