Hi Scott
It is my understanding that the guide scope does not have to be aligned to the imaging scope. It could for example be 30 degrees off the main scope axis. (to find a suitable guide star). If your mount is accurately polar aligned , then the guide corrections would only be in RA and not DEC. If however, you are not accurately polar aligned the your guide corrections would be RA and DEC which is not so good as there are corrections in two different axes.
This is my understanding and if I am wrong please correct me.
