Comes down to how much you cook, doesn't it? The XL will use more fuel, but then again it can cook much more than the LBGE.
Recent posts on here of folks doing three racks of ribs on a mini or small, can't recall which. You will be happy with either, with the WSM you will have a great set-up. Too bad the gasser is toast, they make great warming ovens, place to put the hot stuff and if it has a side burner, great sauce reducer/warmer.
Totally agree, I'm an electric starter kinda guy, if you have power close to your egg there is no better method. Wait eight minutes, unplug it and away you go. I use my Maverick in timer mode so I don't wander off and forget the starter.
I don't think you need to pre-heat it. finish the burgers and then crank her open, drop in the setter and in <10 minutes you will be good to go. The setter will be hot before the pizza stone is, if that's what you meant by pie. If you are baking, raise the pie pan off the setter a bit and the dome temp will be good.
I think Doc does all his direct, no drip pan. I do mine indirect with a drip pan, the setter in. I use a higher dome temp, 450º or so, skin does crisp, but as noted above, dry it off before you cook it.