Thanks Alex. I was toying with a conversion to Losmandy plates although as you say it is a lot of money and I'm not convinced that this is where the flexure is at this stage. I am thinking about changing the vixen dovetail on the 10" to a heavier version (same as my s-b-s bar without the clamps - see bottom of this page
http://www.telescopes-astronomy.com.au/). I would also need a larger bearing surface between the tube rings and the bar to make it worthwhile.
The crescent was very low in the North when I imaged this at Astrofest.
Peter