I looked at the V450s before buying my current RIB and did wonder whether this was why the tubes on the Valiant seem to extend so far aft of the transom.
That said, Walker Bay have since done a similar thing to the Generation, turning my 430 into a 450, with the only significant difference being that the tube ends have been extended 20cm (while the hull remains the same). In their case it was openly stated that this had been done to enable them to up the max HP rating from 60 to 75 - suggesting the extra weight required more tube to be in contact with the water to accommodate this. I suspect the Valiant tube length is for the same reason.
The result is that the deck space on the Generation 450 is no greater than on my 430, and as mine will reach 37mph with a 50hp Honda on the back I can't imagine why anyone would want an additional 50% power (and probably another 25kgs on the transom).
My point is, with your other thread stating that you're looking for a 4.5 - 5.5m RIB, you may find the Valiant (if it has a similar tube length) may not be as spacious as some other RIBs of that length.