I was fortunate enough to have a friend that owned a very nice angled eyepiece scope and used it several times at the range and thought it was the greatest thing since sliced bread.
Cut to the first time I/we tried to use it at long range in the field... We both became so frustrated trying to get it "on" what we had spotted with our binoculars that he dang near threw it away in a fit of rage.
When we got back from that trip we both ordered "straight scopes" and have both been happy since.
It's just not easy, intuitive, or natural to look down to see forward and takes forever to get it lined up, especially when you have your mind on a thousand things other than wrestling with a spotting scope made for birders.
The one I settled on is a Swarovski 20-60x65 and I'm thrilled with it.
The bigger 80mm and larger ones look and work great until you try to pack them or wrestle them in and out of a pickup in the field.
Hope this helps....
If it's long it can't be wrong... LDHunter (Long Distance Hunter) from the Piney Woods of NW Florida. I hunt clearcuts for scrawny whitetails... ;)