The Revo SX only has a mag braking system. The revo s has centrifugal only. The stx has a dual braking system, while the revo premier has the IVCB-IV braking system. I had a gen 2 revo SX and had a love/hate relationship with it. I've used mag brake only bcs for years, but I just couldn't dial that reel in to save my life. I know the new SX has gone with the mag trax system which is different than the linear mag system in the gen 2s and that should make the new SX easier to dial in. Still, unless I need a reel for flipping or pitching, now way my $$ goes towards anything with magnetic only brakes.
I have a Gen 3 STX, and I have NEVER once used the magnetic brakes. I just use 2 of the spring loaded centrifugal brakes with slightly looser than recommended spool tension and my thumb and it performs flawlessly. Once I start pitching and flipping, I'll disengage all centrifugal brakes and use the magnetic brakes. But a reel with ONLY mag brakes?? NO.