I also play a Martin and find that the Elixir Nanoweb are nowhere near as slippy as the original Polyweb. I'm currently using Nanoweb phosphor bronze from Strings Direct for £9.95 a set. They do an .011 to .047 set.

I used to love the sound of new Martin SP strings but they went off so quickly. The nanowebs are pricey but whilst initially not quite so bright as brand new Martins they DO maintain a good sound for several weeks of daily playing. I tried the coated Martins, but they didn't last as well as the Elixirs.

I tried the Newtones and they did sound good and last longer than other uncoated strings but I went back to the Elixirs for the extra convenience of longer life.