I'm using the Great White on my 1" acrylic and it works quite well. I would not say that it is "effortless" to move it around, but I think the amount of effort needed seems about right.
I wrap the outer magnet in a cloth diaper, moistened with brillianize in order to minimize the risk of any outside scratches. So far, this has worked flawlessly for nearly a year.
My only negative experience was with a package of acrylic replacement pads. Apparently, there were some packs of replacement material that do NOT work properly. You can tell the bad stuff because the pad is quite soft compared to the better pad which feels more abrasive.
The softer defective pads stick to the inner surface and you'll pull the magnets apart as you slide.
Algae-Free sent me a replacement right away as soon as they realized what I had.