For $100 you would be crazy not to buy that WSM!!!!
Unless you have a very large family or cook for large groups often, the 18.5 will do most of what anyone with a family of 4 or less would ever want to do. I regularly smoke 4 large pork shoulders in mine for office events (8 to 10 pound shoulders). So a 18.5" will make a lot of BBQ. Never tried a full packer in mine so I can't comment, but like everything else, you could bend or trim it to fit I would think. I do know a full length rack of ribs is too long for the 18.5". I cut mine 2/3 length and stand them in rib racks with two of the 1/3 lengths together if I'm cooking 2 full racks. Nobody has complained about ribs done that way as you end up cutting the racks before eating anyway. Another plus of the 18.5" is it takes less fuel and runs longer per load than the 22" model does. So again, unless you are feeding a small army, an 18.5" is good for most people.
Heck, I'm in Atlanta and if you pass on it I'm tempted to make the drive over to pick it up for that price!
PS - if you do buy it, think about adding a power draft control unit like the BBQ Guru. A power draft and a WSM is about as close to "set and forget" as you will ever get with a charcoal smoker.