I've found the Deep Sky Instruments to be the best due to not introducing any extra errors from mored tools that don't live in an image train.
http://www.deepskyinstruments.com/tr...re_Ver_1.0.pdf
Main issue being is it doesn't account for mirror spacing, but neither do any other daytime methods, for that you'd need a ronchi grating - I was fine with these on my 1600mm but since upgrading to a 6200mm I'm seeing some residual (but balanced) coma in the corners which correct spacing + collimation should fix.
And Geoff I'm pretty its your RC8 I've got - its in a loving home!
