You will like the added space, and a couch will be nice to relax while the kids are napping, or if it is raining.
Unfortunately I think they payload is going to really limit you, especially as the kids grow. Add the hitch, propane, batteries, food, toys, clothes etc to the camper, and you probably have 800-900lbs of tongue weight. That takes you to 250-350lbs of payload weight for the wife, kids, dog, firewood etc.
Unfortunately when you get in the 28' range you really need a payload of atleast 1400-1500lbs in most cases. That means you either need the max payload package in a 1/2 ton, or a 3/4 ton.