Congratulations on your new trike. Very interested to hear how you find the seat after you have put a few miles on it. I really like the look of the hardshells, but was put off after sitting on one [not ice] at Kevins, so went for mesh on the thorax. I have found that I slip forward after a short while, adjusted straps and fitted a piece of rolled up anti slip carpet mat in the leading edge, this has done the trick.
When I visited ICE over half term, sat on the new Vortex, the hardshell with headrest fitted really well, so must be the same shape as the designer. I did wonder how it would be after a longer ride...but reassured by Kevins approach, and chance to try before you buy.