Thanks for the comments.
I've kept the subs to 1 min for two reasons - firstly because 50x5 mins would make for a long session with meridian flips and I don't know how to deal with these from a processing perspective or multiple sessions and all the framing issues associated with my non-permanent setup (and because I'm impatient). The second reason has to do with the histogram while imaging. With 1 min subs I have the histogram almost full so have been worried about clipping at the white end. How is this handled if you want to take longer subs? I can turn the gain down but the Meade forum advise is to not do this.
Great to hear the resolution is good. I went to a fair bit of trouble up front checking the colimation and focus (love that Bahtinov mask).
The DSI is not cooled - just has a heat sink so you typically get Ambient + 3 degC. I've heard of people strapping dry ice to the back but haven't been game to try this yet.
Peter