Perhaps I should add here that
Frontier Optics also sells WO as well as Denkmeier binoviewers, and have been doing so for some years. I was going to buy the WO unit from them, but got talked out of it by the dealer himself (Daniel) who informed me that it is unlikely to reach focus in my Dobsonian. Turns out he was correct.
The Burgess binoviewer I have now only just works with the supplied 1.9x corrector in my 8" Dob. Otherwise I need to barlow it (at ~2.7x) which means I can only use it at high powers (180x and greater), so it has limited use for planetary viewing. I'd need to get lower power correcting lenses but I want to upgrade the binoviewer first - too costly for me atm. Binoviewing with SCTs is less hassle than with Newts (no correcting optics needed).