Cool discussion. My Delta foil has a nose, but it appears from recent photos the newest one does not. I'm about 20 hours into designing a hydrofoil and I started from scratch again tonight, lol. There are some really cool details about building the front wing that are important and are a challenge. I learned a bunch working thru some issues.
Designing without understanding construction is futile. Then there is the practicality of the product for many reasons, both for experienced users and the masses.
Then you have the mystery of laminar vs turbulent flow and how this reacts with your surface design and fluid speed. This can be simulated in a high end system, but my take is a lab would need to back this up and verify the data. For instance, the nose creates turbulence, which almost certainty reduce lift near the root of the wing, but does it delay the separation of flow or does it moreso help the stabilizer flow b/c the turbulence was caused earlier?
Think about commercial aircraft for a moment, they introduced winglets and my take is that may increase surface area contacting the air, but it reduces air drag wrapping back on top of the wing at the tips.
I'm not sure what is best, but as a designer, I'd be looking out for what can sell, is durable, and get good reviews vs what is only applicable for those breaking the sound barrier. Just like relaunch is important for a kite, maybe a nose or bottom vertical wing on the trailing edge can protect the entire foil from disaster upon grounding.
I may buy that manta foil posted above me and go spear fishing once I get better at foiling...
Those manta foils are graphical renderings though...I'd like to see what the nose looks like in a real photograph if anyone has one.