Good grief man, you're in New Zealand. Nothing is a big trip compared to Australia or Europe where you may have to catch a flight to a good kite kiting destination.
The New Zealand Kitesurfing Facebook site, https://www.facebook.com/groups/115325528485030/
has 2,362 members, no doubt some are foilers who are not too far away from you. Talk to them, catch up, swap gear and try their foils. There are also no doubt events in NZ where there are demo days where you can demo a whole range of foils. Doesn't matter that it's not like home, you can still get an idea of the characteristics such as speed, manoeuvrability, wind range etc.
Anhedral, dihedral etc doesn't matter on its own, there are way too many other design considerations such as chord dimension, thickness, thickness across the width of the foil, aspect ratio, shape, stabiliser size & design etc. Each of these will have its advantages and disadvantages, you need to try these if possible in isolation and combination if you want to know what works for you specifically.
One other consideration, try a Flysurfer Peak4 kite if you can, a 3m Peak4 for 20 - 30 knots. It will rearrange your mind about what is possible with a small kite and and a good surf foil. You can turn the kite off and surf the wave with the foil as if you've tossed the kite which is just drifting along above you with minimal pull. May change what you want in a surf foil
Half the price of an LEI kite so much fun!