These figures are pretty consistent with what other people have measured.
As you can see now, the actual magnification factor can change just by changing eyepieces and refocusing.
The widest possible low power field I was able to achieve was using a Baader 10mm SCT to T2 thread adapter, the T2 Prism, and a Mark V attached to the top via the Quick Connector. The light path length for this setup is 171mm.
This will yield a focal length increase of about 220mm.
The Maxbright will result in a shorter focal length increase (as will other similar binoviewers when directly connected) but of course the smaller apertures will restrict you to something like 20mm wide fields, so a 24mm wide field in the Mark V will work at the full apparent field. (IF you put a 24mm Panoptic in a Maxbright, the apparent field is reduced from 68 degrees to something less than 60 degrees. The rear aperture of the BV simply acts like a smaller field stop).
As an aside, if you have a binoviewer that supports very large field stop, I found the 35mm Ultima to be the best compromise between apparent field and exit pupil. The apparent field of a 40mm Plossl will be kind of unrewarding to use. The 35mm Ultima/Orthoscopic/Parks is much more like a standard Plossl.
The 35mm Ultrascopic with the above configuration gave the very widest possible field I got from my SCT. It is only a tiny bit wider than a 24mm Pan, but if you need the extra exit pupil for a dim nebula, the additional reduction in magnification could be worth it.
I don't own this scope anymore but here was my own optimal configuration: