I have both of them but haven't got a chance for comparing them (crappy weather
).
I own the Skyglow for about 8 months now and I can tell you that it works, but not very much. A trip to the next dark observing site would give you similar or even better images. (it always does
). I hope I can check the Ultrablock before school starts again (in 1 week so ...). Lets hope and pray.