Well, my GSO problem still isn't solved. But I am not disheartened.
I borrowed a 0.66 FR unit and have married it to my Astro Professional 102 ED, and it seems to be a match made in heaven.
Last time I tried a FR, I was using a .66 with a Canon 350D on an LX100R, and the vignetting was terrible :(
Still, on the refractor, this combination works very well. The first test of the system was on Monday, very happy: http://deepsky.org.uk/galaxy/m65-m66.shtml
Tonight though, I am reaching for M101. I might see if I can stack some data over several nights.
Here is a first cut of 7 Luminance subs - the RGB data is coming later.