On my favorite Martin dread I like SPs fine, as uncoated strings. They sound great. These days I usually use Elixir PB nanos as they last 2-3x as long between changes, and I don't play my Martin as often as I used to. A lot less work
. Elixirs are nice enough sounding to me (a bit more bright, with less punch that the Martins, IMO). BTW I just tried some normal Bronze nanos (purchased by mistake), and they sounded very thin as compared with the PB Elixir nanos. I use John Pearse PB and DAddarios on occassion as well. I prefer the SPs and John Pearse these days, but have one guitar that really likes the DAddis. Takes some experimenting - another one to consider is DR PB Sunbeams. I hear a lot of guys like them on their Martin dreads - they are "roundwound" which makes them feel a little smoother to me - med set feel like lights. I tried them on an OM size guitar and really like the feel and sound. Life was OK too, maybe a bit better than average non-coated strings. I found the DR coated strings a bit bass heavy, but with a very good feel and a bit less life than Elixirs. Hope this helps!