Chad Adam Browne wrote
1. they last longer
Absolutely! For the first time since the 70's, the frets are harder than the strings.
2. they feel slipperier
True. They polish up to a smoother finish and stay that way.
3. they're very bright
Fallacy. What I have noticed is any fret buzz is a little brighter sounding, but otherwise no difference.
1. they're expensive
Yes, but not much. USA Custom guitars charges the same price for stainless frets as they do for nickel silver. Labour for any work on the frets is usually a bit higher as they are harder to work with and blunt tools faster. On the upside, they last so long that it saves you on fret dresses and on refrets.
2. you break strings easier on them
No. While they are harder than the strings, they make up for it by being smoother, so there is less friction, especially on bends.
I especially like the durability of stainless frets as it means once I have a guitar set up properly with a low action (which is less tolerant of fretwear), it stays that way for years. I used to set up my Sanox with an ultra low action and would have to dress the frets every six months and replace them every two years to keep it buzz free. Eventually I gave up and just raised the action as well as learned to live with a little more fret buzz. Next refret will be SS and then it will probably never need refretting again...