Yep, a kamado in general can be limited on space. I don't have too much trouble with the Big Joe for smoking brisket or pork butt, but if I'm doing ribs I can only fit 3 slabs without a rib rack. One of these days I'll need to get a rack if I have a bigger group. If I'm doing something like buffalo wings, I can only do about about 32 wing pieces. I might someday try to get the KJ grate extender for just that purpose though.
Generally the Big Joe (equivalent to the XL BGE) is enough for a family of 4-5. I have trouble understanding how people feed a family with just a Large BGE, and the Medium seems like it would be VERY constricting.
Though a medium BGE alongside another grill/smoker makes a lot of sense. I also have a Joe Jr (equivalent grate to the small or Minimax BGE), which is great when I'm just cooking smaller things for just my girlfriend and I, or 4-5 burgers for the family...