I never see much written on them...looking for 8x50 SLC, trinovid feedback...
All 50mm models seem pretty heavy. They are somewhere between birding and astronomy, mostly used by hunters. Astronomers use big mounted porros.
The Nikon Actions go from 8x40 for all use, to 10x50, mostly for hunters. I think the holding of the binoculars takes much less of the time for hunters than birders who spend long minutes looking, at times. Most of the time of hunting is looking, listening, with nothing happening out in the fields. The hunter may think he needs 10x in low light, myth or not, and does not always want 8x50 or 7x50.
Also, if you do not need 50mm, why pay for all that polished expensive glass? Some $1,600-1700
Here is some propaganda on 8x56
http://www.eagleoptics.com/index.asp?pid=4246
I think birders tend to avoid the 8x50mm models because most people want to carry less weight and they also want a wider field of view. Some 8x50's have a significantly narrower field of view than the equivalent 8x42. Personally I really like the 8x50 format (I'm a sucker for those big lenses) and used to have the Trinovid 8x50 BA. Optically it was one of the best binoculars I've used. I sold it in the end as I didn't get along with the ergonomics (I find the 50mm Ultravids much, much better) and this made them feel even heavier than they were. If I bought another 8x50 I'd take a close look at the Swarovski SLC or Ultravid before deciding.
Cheers
John