I've got the worlds (actually Rod now recommends picking one up in his used gudie) only "very good" C90 which is my travel scope. I've got the LAR and use a Lumicon 1.25" diagonal and the views are as good as any ETX I've seen (remember a C9o @ 1000mm has a much wider FOV) and quite a lot cleaner than the G185 I had (don't you have one of those also?).
I do and I have had some good times with it, I also have a Pronto which is physically larger but gives superior views, especially with 2 inch eyepieces. 5 degree FOV are possible.
I use it with my focal reducer and have a f6.3 scope that with a 32mm plossl gives extremely wide views in a scope that fits under the airline seat with 4 ep, barlow, whitelight sun filter, Red LED light, my PDA with PockeySky.
A C5 also fits nicely under the airline seat and has substantially greater aperture which makes viewing DSOs quite nice. But I would think that C-90s must show substantial vignetting with a Focal Reducer and a 32 mm eyepiece or some such thing., or so it would seem, the hole is the back is just not that big...
Taken it to Mexico, Az., Hawaii, and on every driving trip my wife and I take. Also it is a great digiscope for my Nikon CP4500. So I just can part with it. Thats also why the 1278 fit my scope stable.
I have the Orion/Synta 120 mm F8.3 scope which should be quite similar to the BO 1278. It does a good job on double stars but the OTA is 40 inches long or so, not airline portable and my 8 inch XT-8 is a better overall performer because of the increase aperture. Thats why it is for sale, just don't use it.
I order the 1026 because I was thinking that the 102mm objective would provide brighter widefield views than my Pronto but still be reasonably small. My guess is that it should be comparable to the C-5 in many ways but probably give those refractor views that don't always happen with Reflectors.
>>BTW do you have a focal reducer for you C5, you will like what it does for a SCT. except for planets I never use my C8 without it.
I have one, it brings the focal length down to 800mm. Which is essentially one eyepiece step. Nice for Widefield viewing but then when I want to use some magnification, then it requires a barlow. With a smaller aperture, I try to avoid getting too much glass in the optical path. With a C-5, focal reducer, and barlow, there the corrector, the primary, secondary, a couple of pieces of glass in the focal reducer, about 3 in the barlow and then the diagonal, this all preceeds the eyepiece.