Peter,
There is not much difference between the top brand spotting scopes. For digiscoping the eyepieces and adapters are very important. The camera you choose could be more important than whether you choose Nikon,Leica,Swarovski or Zeiss. I have left Kowa out because they have a new range of 88mm scopes which are supposed to be very good but they are still not launched here and there are very few in the field after 1 year from launch in the USA.
The biggest difference in quality for digiscoping is the distance and the quality of light. In Hong Kong our light is very hazy to dull for most of the year so the bigger the objective lens and the brighter the eyepiece the better.
The advantage of Nikon is that you can the full system from them and they have a wide range of eyepieces. Their price will be a bit better than the European brands.
I'm on my second Swarovski scope ( my latest Swarovski STS80HD was donated by Swarovski USA so I'm a little biased ) and with the 30x eyepiece and their DCA adapter it's been a wonderful scope. I've taken over 250,000 bird photos with it.
Neil.
