Test frog from here - Frog by Owenscenic - it's the little one test frog.stl (there is also a big one, I may try later)
So I printed the first frog (placed in the top right in the photo below) and he had quite a lot of brown bobbles on his left hand side (the side closest to machine 0 - origin).
So on the next test print I re-enabled the shield option (frog on the bottom left) You can see that the shield wipes off the spare ABS and stops brown bobbles, it also seems to make less string-bits and gives a better overall end result.
Compare the Frog ! - Left with wiper-shield and Right without.
Prints are sticking really well now to the Kapton tape. - but I may have problems when I try to print larger parts.
Some close-ups for a review of Quality -
This is the underside of the above frog, nice and glass-shiny, and the next layer looks well fixed to the base.
This is a close-up of infill using a 0.8mm infill gap, looks quite a nice uniform hatch.
This is infill with a 1.5mm spacing, slightly more sag.
Overall I'm very happy with my basic pinch-wheel extruder, I didn't think it would be very good and I expected to be wanting to print a geared replacement ASAP, but at the moment I'm having too much fun printing other stuff, mind you a big gear would also be a good test...
On with printing -