I'm trying to learn a little about how the tail angle effects flight. I have watched the YouTube vid by delta hydrofoils however I'm actually more interested in relation to just surfing foils rather than with a kite so wondering if the same applies or not.

Yep. Same applies. More aoa of the rear wing will increase stability, decrease stall speed and decrease top speed. You will stand further forward on the board and further back with less aoa.

Less aoa increases maneuverability top steep and stall speed.