I found some interesting stuff about them. I dunno it seems maybe worth trying if it won't cost more than the flipflop. I'm thinking 36h too but don't know if that's a good idea or not 32h seems to be more available in some stuff.
A flip flop hub is much simpler than a two speed and yet they cost about the same? There has to be a qualitative difference in that case.
Find an old F & S 2 speed, otherwise stay single.
I found some interesting stuff about them. I dunno it seems maybe worth trying if it won't cost more than the flipflop. I'm thinking 36h too but don't know if that's a good idea or not 32h seems to be more available in some stuff.
http://mccraw.co.uk/sturmey-archer-s2c/
http://mccraw.co.uk/sram-automatix-review/
This mod too.
http://bikesfornoreason.blogspot.co.uk/2014/01/sram-automatix-2-speed-hack.html