I wouldn't claim to have a "ton" of time in the P14, but from what I could see in the few times I have paddled one it is more maneuverable than its 1" of rocker would suggest. I think it's sort of like the Penobscot 16 in that way, perhaps a better downriver boat than a whitewater boat. It really is a prospector in design - jack of all trades, master of none. I would still love to try and compare it to the Nova Craft P14. As far as center depth, I am actually surprised that it's smaller than the Phoenix - with respect to freeboard the P14 doesn't feel lower to me when I've paddled one. I wonder if the hull shape keeps it higher up in the water than the more rounded Phoenix? I may be totally making this up however.
To me the big things the Phoenix has over the Prospector 14 are a 2" narrower hull making it more sleek / faster and a more rounded bottom, faster to heel. Plus of course the IXP layup is amazing. But I'd bet money the P14 will haul a bigger load and be more stable doing so. The others you mention I wouldn't lump with the Phoenix and P14 personally, more "hotrod boats" that are superb river trippers to be sure (especially the SRT and Supernova), but also require a deft touch or you will be swimming down that river! Not that you couldn't flip a P14 or Phoenix (heck, I've been known to flip an Old Town Camper at times

), but they are far more forgiving than the others...