As for the truck question, that is another small issue. We have a Dodge 3500 but it has no gooseneck hitch installed. If we decided on the 3 horse, we'd have to shell out another $600 or so for the modification.
In Virginia, the temp's are fickle. I've been to shows that start off raining in the morning, turn into a nice breezy perfect day on the way to the show grounds, and once it's time to ride, it feels like it's 110 degrees. We've put up with a bumper-pull for several years by now, so while we are used to sitting in the sun (or rain) the most tantalizing feature of the gooseneck is the canopy. However, like Vida pointed out, that can be added to the bumper-pull later on if we desire it.
The only other thing to consider is the storage. We could keep the bumper pull at our house but the gooseneck is too big. It's conceivable that I could keep it where I work, but that would add another forty minutes to our drive because it's in the opposite direction of my horse.
It's looking good for the bumper-pull at this point.