The winner will be
All of us "sail fast with wings & foils" fanatics.
I was disappointed when the the winged moth attempt fizzled and then was snuffed out by a vote.
However, with SR2, AC 72s and the C Class (getting even more interesting than ever before) we are getting a real show.
Unless the whole "wings + foils" fever chills out (which I doubt), we may yet see foil/wing improvements that have a chance to "trickle down" to a new class, a product for an existing class, or some options for the "lets see how this works" do-it-yourself types.
OK now back to the intended topic.
I became a fan of the OR design team shortly after they went from soft to hard for the Dogzilla rig. However, being an OR fan does not mean that I not impressed by ETNZ.
My bet speed will win and win big. I would put the chance of a slightly slower boat winning due to better handling as very slim.
The OR boat looks to have more of a speed focus.
The ETNZ rig looks like it has the potential to be better, but OR have been at wings longer and probably have more geek power behind their wing. Just no way to pick at this point.
Foils are the key. Foils make the biggest improvement for the downwind legs, but I bet that both boats are going to be close enough on the downwind. If one team really is distinctly faster on upwind VMG, victory is theirs as long as they screw up too much. Both teams have been seen just ripping along, but without side by side runs or real polars, their is just no way to say who is fastest now.
Both teams also have serious potential for tweaking more top speed. Big foiling winged cats are just too new to be anywhere near optimum. However, development time is limited.
Dagger foils are the most important item, but are less practical to "tune". OR has a slight potential advantage here with two boat testing ability.
Rudders stabilizers changes can only do so much, but are easier to play with. OR has talked about reducing rudder stabilizer area for more speed. I have seen no mention of a similar effort by ETNZ. However, since they (and LR) did no go along with the proposed minimum area requirement, they have retained the ability to consider a similar option. For each team, they probably have a pretty good understanding of the other teams apparent performance. If they think they are ahead, they can stick with a conservative large area to preserve PP avoidance safety margin. If they are ahead but close, they could consider working out the details for something faster but holding off to see if it is worth the risk. If they think they are behind but close, the could plan a "just in time" implementation to try to turn the tables. If they do not think a small speed increase would help, they could consider sticking with a safe and very reliable configuration and hope that the other guy messes up.
Unlike most, I am not picking a winner but did take my best cut at the "why". It will be the boat that has the better upwind VMG in September.