Just back from a visit to Jim & Carol Zipp's store in Hamden, The Fat Robin, where we put a few scopes side-by-side for comparison. I had a nice long look through 3 scopes:
#1) My ol' Swarovski AT 80 HD with the NEW 25-50x Wide Angle zoom eyepiece
#2) Swarovski ATS 80 HD with the new 25-50x Wide Angle zoom eyepiece
#3) Kowa 883 Prominar with 20-60x zoom eyepiece
First off, I was pleasantly surprised that the newest Swaro eyepiece fits my current scope (note: the eyepiece does not lock into place, but it is still very secure). But in direct comparison to setups #2 and #3, this combo did not stand up. The newer Swaro body and Kowa were both obviously better throughout. So much for my cheap idea of only having to upgrade the eyepiece! It's apparent that the optics of my old scope have been surpassed.
Next I put #2 and #3 side-by-side. The weather was overcast but, cloud-cover considered, it was fairly bright. Both images were outstanding. It was immediately apparent that any differences were slight. As the reviews have stated, the Kowa was a touch brighter while the Swarovski's FOV was wider, with the differences most notable at high magnification. I would expect the brightness of the Kowa to really shine in low-light morning or evening situations. With the Kowa at 60x the image is still incredibly bright and crisp.
Kowa cost: approx $2600
Swaro cost: approx $3000 (~$2300 for the body and ~$700 for the eyepiece)
**Note that the Swarovski ATM/STM series, which I noted in my first post about scope research, is $500 more than this combo. The ATM/STM series, as far as I understand, is optically identical to the ATS/STS series...it differs in the magnesium composition of the body, which saves a few ounces of weight. I can't see paying $500 for such a small change.)
Now a bit on digiscoping:
Both brightness and FOV are important when digiscoping, so it appears that each scope has one advantage over the other. Kowa also makes a 25x Long Eye Relief and a 30x Wide Angle fixed eyepiece, which each go for another $340. The Kowa with a fixed eyepiece might give the best of both worlds, as the FOV on the fixed eyepieces is much improved over the zoom. This additional expense would bring the total cost of the Kowa up to that of the Swaro at ~$3000.
Well, I have a decision to make! The good news is that either way, I win :)
Much thanks to Alex Burdo for suggesting that I re-consider the Swarovski ATS/STS line of scopes. You were right on, Alex. They are superb.