I bought the Gan 15 Maglev with UV coating as a potential main. Regular price for the Gan 15 is $70, but I was able to pick it up during SCS Black Friday sale for $60. I performed 500 solves on this cube before posting this review. I purchased SuperNova service from SCS and have added Lunar lube once. I have the cube set up on center travel adjustment "5", tension adjustment "5", with the green magnet rods (stronger).
PROS
Smooth and quiet during metronome exercises, getting progressively more clacky as the TPS increases. This cube is a bit quieter than the Gan 12 regarding magnet sounds, but louder regarding plastic sounds. Twisting is easier, more airy, than the Gan 12. Corner cutting is really good at speed, and the cube really rewards fast turns. It will forward corner cut a little more 45 and backward cut up to about 22 degrees at my settings. Corner cutting will improve with looser settings, but isn't necessary. I prefer UV coating on stickerless cubes, and Gan has one of the best coatings out there. With the magnet rods I'm using, the click and 'bump' during turns is softer than the Gan 12 and the auto alignment isn't as strong, though still works from about 15 degrees with a slight nudge. The plastic feels nice and twisting is very forgiving. The price I paid for this cube represents a really good value, with the regular price being about right.
CONS
Removing the center caps cannot be accomplished without the provided tool. Adjustments can't be made without the provided tool. Although there are three differents sets of magnet rods, the magnet strength on the corners isn't adjustable. If I'm being picky, the plastic "clack" is louder than I prefer, although this is normal for high TPS on almost all cubes. This isn't an issue unless I'm spamming solves while the family watches TV, or in public. In those instances I'll select one of my quieter cubes.
VERDICT
This is a great cube, and if you can pick it up on sale, at a really good price. Although the turning feel is better than the Gan 12, I like the ability to adjust corner magnet strength on the Gan 12. I typically set my cubes up looser, and deal with the instability in order to get better turning. There is no reason for me to deal with loose settings on the Gan 15 since it turns great even at tighter tensions than I normally use. Although, even at slightly looser tensions, the cube remains fairly stable, though it does get harder to control. On it's own, I recommend this cube if you don't already have the Gan 12 since it is very enjoyable to twist. I'm not certain it's an upgrade over the Gan 12, though. There are aspects that are better (turning feel, slightly) but there are aspects that aren't. I really enjoy using both of these cubes, and not surprisingly, my AO100 are very similar between the cubes.