I have the KOWA TS501 with 20x angled eyepiece. I love it! It is extremely light and compact, much more than I expected. I am concerned about taking it to the field, but these are carried by birders all kinds of places so I'm sure it will survive. I got mine from Jim Owens at jarheadtop.com , he has some good deals, and he's a real friendly guy to talk with on the phone. I had looked through various scopes under $200, and even purchased the Burris Landmark 15-45 x 60 from Natchez for $138 (with a little plastic tripod). I returned it after seeing how bad the picture got when I zoomed it out of 15X. You lose the eye relief also.
I use the KOWA in my garage also for 25ft. targets with my air rifles. I have to say again, this is a great scope! Sorry I can't tell you anything about the Nikon, I had thought of ordering the Earth & Sky but didn't after talking with Jim and ordering the KOWA.
Just wanted to add that I read a review somewhere of the TS7_ _ ? ( the old 77mm, no longer made but still available from some sources), and how the eyepiece would fog up sometimes. There's a guy who makes a cover with a quality glass lense that fits over the eyepiece and keeps it from fogging up. If I find the website I'll post it here for you.