Guide scopes are for the birds Peter.
Roland Christen recommends guide scopes being mounted directly to the OTA of the imaging scope not onto the guide rings. Not sure if that is your mounting method. I have also read recently where a marketing ad for mounting rings promoted no felt to prevent flex from the felt in felt lined rings.
Guide scopes are really an old fashioned setup and are problematic. I've never had a guide scope match the accuracy of a MMOAG.
But sometimes you may have no choice but to use one. If I put the reducer on my CDK17 it virtually has no backfocus so a MMOAG is out of the equation and a guide scope has to be used.
I use a Vixen 110mm compound scope. I forget the designation VMC or some thing like that. It worked well and is 1050mm focal length.
I also have an Astrotech 65mm ED which works fairly well.
I think you can get a slight improvement in autoguiding accuracy with 1x1 binning. I think its usual to use 2x2 only to help remove artifacts and to increase sensitivity. Autoguiding is supposed to calculated down to fractions of a pixel so the difference is small.
Did Maxim ever get there multi star autoguiding working? Pehraps that may help. Otherwise using guide scopes is going down a dark path
Greg.