This is my view on cambered inflatable SUP boards with a negative rocker in the middle:

There are boards that try to compensate the bending of the board under the weight of the paddler by designing in a camber in the middle: a negative rocker. This gives a 'W' scoop- rocker line when pumped up and should bend to a perfect rocker when the paddler is in the middle of the board.
Just check the websites of different manufactures: the do mention the camber as the ultimate solution. However it is far from a decent solution.

1) The depth of the camber is calculated for a specific weight at a specific pressure of the board. Suppose it has been designed for the average weight of 85kgs then anyone weighing lesser than 75kg will have a board with a slightly negative camber/rocker in the middle as he isn't heavy enough: this will slow down your board significantly.
For those who are heavier the board will bend more than intended.
These boards are only great for the weight they have been designed for. Anyone weighing a little less or more will not have a board with the intended scoop-rocker line.
Thus even paddling on flat lakes and rivers will require more power in order to move forward.

2) In waves the negative camber becomes even more a hinder - even for those with the perfect weight the board was designed for. With the perfect weight catching the wave will be fine, but once on the wave surfers move backwards then camber resurrects slowing the board down considerably while driving down the wave face as the scoop-rocker line has obtained the 'W' shape again. This will not only slow down the board but also decrease the maneuverability as the scoop-rocker line is awkward requiring more paddling to keep up with the wave. Similar happens when the surfer moves to the front of the board bending the nose down and probably creating an even greater negative camber in the middle which will slow down the board.
The lighter paddlers will have the negative camber all of the time crippling the performance.
The heavier paddlers will also have a camber being at the back of the board as their weight is not positioned on the camber - similar when they are on nose of the board getting a camber in he middle.

Negative cambered scoop-rocker lines are a bad design - it is a compromise with limited effect and only for those with the weight the design was intended for.

Solution:
The only methods to get a stiff board with a really stiffened scoop-rocker are:
- High density drop stitch (6 per inch or more)
- Allowing high pressure (>20psi)
- Stiffening with lateral battens
This will minimize the deformation of the board.
Of course the lesser the weight of the paddler the better the scoop rocker line will be maintained: in the middle, at the back or at the nose of the board while surfing.

Just my view.

Agree and disagree, depends on what your intended use is. My wife and kids are big fans of inflatables, we currently have a 10' Hobie that has some camber and on flat water (which is their only use for it) the camber flattens out and the board works well. Don't overlook one feature of inflatables - that they can be rider-tuned to some extent by moderating pressure, especially for lighter riders. the hobie glides better in flat water than rockered inflatables we've tried, that induce more rocker with a rider on them. We've also experimented with a couple of demo 12'6 pump ups with camber and in flat water at recommended pressure or above they work OK for me (a heavier paddler) but the camber seems to interfere with flat water stability and performance for the wife and squids. Dropping the pressure a few psi allows the camber to flatten out with a light paddler on board and definitely allows the board to work better on flats and small chop/ripples with a light paddler on it. Seems a bit of flex allows the pump-up to conform to the water surface and run better (up to a point anyway...similar effect is seen in surf mats, where a bit less pressure allows them to conform to the water surface and they run faster).

So camber is helpful (and can be tuned) in flat water situations but reckon you're right in saying that this all goes out the window in surf and bigger runners, where things get a bit weird with camber. All that said, we're not that fussy about performance wih our pump up, it's more about convenience for Mrs C and comfort for the kids.