Not having ever installed the "toppers", but having seen a number of them.....they all tend to push the first row of shingles upwards, potentionally causing a leak as it can turn what was an adequate pitch into a low-pitch.

I don't think there's any meaningfull difference between the "brand name" versions and the generic ones....other than the ridiculous price they charge for the brand name...in order to cover the massive TV, Radio, Newsprint, and famous talking head advertising.

A roof CAN be your "friend"...rather than "that thing you hate".