I had soma single (crappy...) and i upgraded to soma doubles (got em for cheap.. 20bucks). IMO way worth it.. the ride was much better. I can't quite explain it.. you'll just have to try doubles for yourself! But if i have to list some reasons why double is better.. for me are:

-more binded in
-easier (zomg) skidz
-overall better/more comfortable ride
-foot more snug/stable...