Personally I’d pass on 80mm systems for hunting if carrying around in a pack. The 65’s do great plus lighter and smaller. Any reason in particular for wanting the 80’s?
Good point on them being smaller. On my spreadsheet the TSN-664 comes to 7.98 lbs after I add in the adapter's weight. They have 68.42 cm^2 so it's 8.57 cm^2/lb of performance. I had previously ruled them out as at 7.98 lbs makes the 80mm a no brainer weight-wise. I didn't think about dimensions though in doing this exercise.
I'm also concerned with exit pupil too. At min zoom the 66s has 2.64 exit pupil vs the 3.20 of the 80mm, or 3.52 of the 88mm. So the Swaro 80s will have better low light performance in not just resolution but eye box.
Then I forgot to mention in my first post I wear glasses, the Kowas has 17mm of eye relief while the Swaros have 20mm. So that is another consideration of mine that makes me lean towards Swarovski.
I also forgot to mention I have some swaro NL pures 14.7x52s - so outside the ability to zoom on 65s, I don't feel going from 52mm -> 65mm would be a big enough step up for me.
I also forgot to mention I do western style hunting - elk, mule deer, new mexico oryx & ibex, pretty much any big game hunt you can do in the west I do. My first off range NM oryx took almost the entire month doing it every day - and that hunt personally taught me that I need better glass. At the time I only had some mid range 8x42s binoculars, and a low end 20-60x80mm conus spotter.
I'm thinking if the 65s do a great job for you then I think the 80 swaros will definitely do a great job for me.

I still have some "what if" concerns if I went with those vs the kowa 88s.
Like for NM off range oryx - that's not something you're packing in, but driving miles and miles of hill looking at desert cactus to spot two horns and a clown face out in the wild

. I definitely think 2x 80mm swaros would be a huge upgrade vs what I have.
Do you have any more thoughts on my situation?