Hi motogon,
I honestly think there is too much varied information about board shape and it's relevance. The new shapes from Duotone/Fanatic is all about making as small a board as possible with the largest amount of volume. By removing bevels they are adding a hard release edge and packing volume into the vacant space where the bevel was.
As most experienced riders are riding boards with volume in litres equal to, or less than their body weight, the majority of the board will be underwater or at least deeply immersed. The hard edge and full volume will aid in getting up to speed,and releasing from the water, but the speed isn't the issue when using a high aspect foil.
I mostly ride SABFoil W1110 and 1150-L or 1350-L high aspect foils in the 9.5-10.5:1 ratio and I can pop up onto wing with one pump of the back foot with a board with slight bevels. I ride an 80lt board and weigh 100kg and can start in light and strong wind equally easily. The bevels are more about giving a softer touch when you are mid turn and your rail touches the surface. Hard rails are not as good for this issue as they tend to bite and assist in crashing.
So speed is not an issue to water start, the volume in the tail definitely gives a pitch stability advantage over bevels. If you are talking about high speed low surface area wings, then speed is critical and release edge is critical but for HA, I feel board shape is irrelevant.
The two boards pictured are the:-
Fanatic SkyStyle 5'1" which has 85lt, and 24.5" width. Hard rails and hard tail.
SIC Raptor 5' which has 80lt and 25" width. The SIC has slight bevels on the rails and tail.
I find the Fanatic board is harder for me to water start due to sinking the tail enough to hook my foot up to get to my knees from straddled. The Raptor is less stable in pitch which makes it easy to sink the tail and get my foot aboard to easily get to my knees. Keeping in mind the entire board is underwater when I am on my knees and not moving. I have ridden both boards and like them both, but for me, the SIC takes the win for reasons mentioned above, it tends to also be a little more forgiving in a touch down, but is less
stable but easier for me in starts.
I hope this has been helpful.
DM