From what I can tell, the biggest advantage and disadvantage (aside from the price), is its design.
It has a shorter height than the other brands, so it doesnt cause an unnatural angle on the shift cable. That is the one thing I didnt like about the Boomba. The gears that are on the short side, meaning when the shift cable retracts (2nd & 4th in particular), felt like "murky, like stirring thick oatmeal. If you look under the hood when in those gears, it looked awfully kinked at those positions.
On the other, Mountune's design requires you to remove the pivot ball from the shift cable lever and re-use it in the adapter. This makes the install a bit more involved, but mostly importantly for me, it makes it a pain in the ass to return to stock. That might not be a problem for most people, but I'm kinda indecisive about modding in general (as you can tell, since I already reverted it back to stock), and much prefer mods that are "slip on, slip off".
2017 Magnetic FiST w/Recaros