I've only used it for terrestrial viewing so far. It has the PGIII and BB coatings. A few comments.
It took months of waiting--delivery time kept being put back yet another month. Communicated with the Jims at Questar quite a bit.
When I finally got my order, one of the eyepieces was bad (Brandon). Jim said when I described the problem he knew exactly what caused it--the lens had somehow been installed too tightly or some such. I returned it and another is on the way. (Why didn't the exquisite Questar staff test it before sending it to me???) I mean, this is the RR of telescopes right?. Jim R. actually kept stressing that during one of our conversations.
The manuals sent with the scope were vague, confusing and out of date in a lot of ways. Some parts sounded like it was written in the 1960s. A couple of very key nuggets were omitted when it came to setting up the hand-held device for the PgIII which had me angry and frustrated, so much so that I was getting ready to send the whole thing back for a refund!!! The hand controller device is configured for future models that don't pertain to my configuration, and if they had bothered to at least put a note in with my order, telling me just a couple of key settings, I would have had NO problems. As it was, the drive appeared to not work at all, and I was getting a bit miffed. I finally got things going after walking through on the phone with Jim P. So now all is cool. Haven't gotten it under dark skies yet, but hope to soon.
The eternal question: Are Questars worth the price? (I forked out over $6k for this baby)
I guess it remains to be seen. The thing is a joy to just look at, and another joy to be able to carry around like a book or something. As far as the actual viewing quality,. my eyes can't really see much difference between the Q and its Brandons and my old C-8 and its eyepieces. I guess I'm rambling a bit, but I can only say it is worth it if you can spare the money and want one for whatever reason. The guys at Questar are ALWAYS available by phone, and that means a lot. They also do seem to want to please the customer (wise policy, considering the prices), and Jim R told me that they will always be there to provide even after warranties expire. One other thing is, I would not have expected to see ANY speck of debris on a mirror in the tube, but there are a couple. It really doesn't affect the scope performance but I was a little surprised. I also have a $180 c-90 Celestron and for the life of me cannot spot a speck of anything on its mirrors.