Magfloat max about $30
Rare Earth upto $180.....for me it was a nobrainer....and the magfloat work fine for soft algeas. I use a scraper for coraline
I think if you have glass thicker than the 5/8 limit of the magfloat only then shell out the extra cash....I hear it takes both hands to move a good size rare-earth mag
I don't think that even the rare earth could scrape coraline ,for long.
Oceansmotions make a scrapper out of a magfloat, as an added bonus
My 2 cents
Cheers