In the pecking order of scopes, in my opinion, the Diascope would be up there with the best. I have the 85 T-FL - 20-75 zoom & I can't fault it. The only draw back will be the FOV at 75 but I phonescope with it & the results have been excellent. I've tried Kowas & Swaros & can't see any...
If there's one big difference, I only ever see birds & may be a few dear....there certainly aren't any Grizzlies or Wolves in Britain other than in Zoos & Safari Parks...so you certainly did benefit by buying the Kowa etc. Let's hope you sell them all.
Unlike you I have not been a photographer for as many years as you. I started as a birder progressing through scopes & old bridge cameras, to better scopes which would enable me to phonescope. ending up with a Zeiss 85 T-FL (20-75), adapters & S10 phone. The video results, in my...
I've got a 2012 black version with a 'new' (replaced by Zeiss last year) 20-75 zoom & have been extremely happy with it. I phonescope with my Samsung S10 & PhoneSkope adapters & get great results. In my opinion the Diascope is a brilliant bit of kit.