Mike, If you are manually guiding a longer focal length guide scope will give you better results as any drift of your image is noticed more in the guide scope do to it's longer focal length.
Clear as mud
I used to do Off Axis guiding through the main scope, 12.5" F6, as any shift of the image either through flexure or drift was real, but finding a guide star bright enough sometime took as long as the exposure time.
Hopefully my 250mm F6 will be ready within a couple of weeks and I will go down the same path as you.
Alexander