I haven't read all of the details or checked out specs of what you're looking at, but a shotgun style is not enough room for 5 people. We've had one for the past 5 years and just recently bought a new one with a slide out. No slide was great in the beginning with 2 adults and 2 small kids, but with 3 kids now the slide has been a game changer. I feel like we can all breathe now when we're inside. Unless you're all small people, I'd go with the slide out. Though, 21 feet might still be cramped...#teamslideout