I didn't own the Nikon until 5 years after my first book published, so was using the "ol' Pirate" extendable Swaro' CT 30x fixed scope then (still a killer scope)
Went to ED50 in 2019 for about 4 seasons, and then to the Swaro' ATC 17-40x56 and now the Swaro' STC 17-40x56.
I hear the small Kowa 553 is neck 'n neck though, if you missed
@Matt Cashell review, it's here:
Swarovski ATC Compact Spotting Scope Review. Full optical evaluation of the Swarovksi Compact Spotting Scope.
www.rokslide.com
but if you already own the ED50 and are happy, stay happy and run it. especially with the upgraded eyepieces, it's still pretty dang good for the money