"I'm thinking that the BGE would (a) last longer and (b) kill several birds with one stone..."

Bingo! That's exactly the thinking that drove me to the BGE. If you are just grilling, there are cheaper options that work just as well. If you are smoking a bunch of meat all the time, you'd want a dedicated smoker. But if you are doing all of the above, the BGE is great.

BTW - if you are really looking at just doing one butt or a couple of chickens, you might want to look at the medium BGE. The grid is just 15 inches across, but it can still handle a pizza, or 4 steaks, or 2 butts.

Costco has had both, but note that they are not an authorized BGE dealer so you may have warranty issues if you pick up a BGE there, depending on how stand-up BGE corporate is.

Apples and oranges - the OP was looking for a BGE alternative. While the Weber kettle is a fine grill (I've owned and cooked-through 2 of them), it is not (IMHO) a BGE alternative.

Most ceramic kamado cookers can hit a temp of over 1200°F for the best steaks ever, bake pizzas at 500°F, and smoke brisket at 250°F for 18+ hours on one load of lump. I enjoyed my kettle grills, but there's not one of them out there than can do all of that without some major modifications and/or user intervention.

All ceramic kamado-style cookers will produce similar results. That said, I love my BGE and wouldn't trade it. Part of that is because of the warranty:

Big Steel Keg has a 5 year warranty.
Primo Grills covers the ceramics for 20 years and metal parts for 5 years.
BGE offers 3 years on plate setters, 5 years on metal parts, and lifetime on the ceramics.

If you want the best price on a BGE, wait for an Eggfest in your area and then contact the dealer about buying a demo egg (used just for cooking at the fest) for about 2/3rd the usual price.

At 25 pounds, you might be pushing how much bird you can put in your large (I'm assuming you have a large) Egg. Do a test fit with the plate setter, roaster, and a basketball in place of the bird. You have to watch to make sure the breast isn't touching the dome thermometer.

If it is touching, maybe think about spatchcocking or breaking the bird down into white meat and dark meat: http://www.food-fire.com/index.php/20...

The last time I did a whole (non-spatchcocked) turkey on my large BGE I ran it up to 500°F, tossed in a chunk of apple wood and loaded the cold plate setter (legs up), a trivet, the roasting pan full of turkey, and then closed the lid. The dome temperature stayed at 500°F for about 5 minutes before dropping. I watched the thermometer and adjusted the vents to get the dome down to 350°F for the rest of the cook.

The turkey cooked for just about 4 hours total (roughly 15 minutes per pound), to the point where my Thermapen instant-read thermometer said the thigh was at 180°F and the breast was 160°F. This is a nice way to get a crisp skin and an evenly-cooked bird.