Don't pay attention to the 'gallons' ratings in a brochure, there is nobody to regulate that so its simply at the discretion of the manufacturer how to measure that number. If you are concerned about size I would sit in it dry or more ideally wet test it. I've personally soaked in a Flair and the only concern (depending on how many people you want to soak together on a regular basis) is the footwell area is very small, 1 person in the lounger and I personally wouldn't want more than 2 others, maybe 3 max for a total of 3-4 adults in the spa or it would get really tight.
