I have a set of the PA's, (just the PA's, I haven't got the extensions for the narrow cuts), and use them in combination with a 3m guiderail to make repetitive cuts out of full sheets by myself. I haven't used them on a shorter guiderail, but then I can mark the piece without walking around, and see both marks when positioning the rail, so there's less need for the things then.
So far I've used them for cuts between 20cm and 40cm wide, and they have worked out well for me,.
I've documented the first time I've used the things with some pics from my cellphone: link to thread
