The c90 and C5 can only use the simple .63 reducers, the baffles are too small for the AG.
The baffle AG version is like the Edge HD, in that it puts the optics inside the baffle, and I believe that's what makes it so comfortable to the eye in use. The focal length of the TC is, IIRC, longer than the .63 types, giving that much more freedom of locating the eyepiece. Baader has a range, and my full 2" setup is at the longer part of that range, but still produces great images.
The clear aperture is much greater than my M or C .63 TCs. Badder makes a big deal of their difficult to make super thin AG tubes. Vignetting? None visually noticable to me in a maximum true field of view 2" ep (30mm 82 degree). Even when tested on a light color cement wall.
I bought my .63 Meade and Celestron decades ago and never use them since I do find the vignetting awful in a wide 2" setup.
Only AG in baffle tube or the Maxbright + AG version have satisfied me, but my market sample has been tiny, only 1990s M and C versions. But I cannot see newer ones of similar size working any better, for me.
So, personally, I'd not go to the conventional .63 with a 2", for visual, unless there is an oversize one made specifically for the task.
The body SCT thread I mentioned was a diagonal with actual SCT threads cut into the main body for the normal smooth nosepiece. Using the ring style like you have will add at least 20mm of back spacing and may not work at all.
Getting a Baader T2 diagonal, whether the 'big' one or the 32mm prism 1.25, is the best way to do it. Even with a body threaded 2", I use a 3 part adapter stack. No recollection now but it wasn't cheap.
The T2 32mm will also allow use of the Maxbright on a C5, my orange tube has limited focus range, but there really not enough aperture for me, personally, to enjoy. But who knows if I change my mind over time. I could not reach focus without the T2 diagonal plus Maxbtright.
Going back to the core topic, the long SCT and Mak f ratios normally seen are pretty tolerant of almost any ep. I have ones that I like better than others, but everything does at least decently. Not like those short dobs!
Edited by markb, 19 September 2021 - 04:26 PM.