I did run 1x9 for a while on my Blizzard, it made the bike look very nice and simple and there was obviously less to go wrong.
I did a 12 hour race last year and my knee eventually blew up which led me to putting a granny ring back on. For events like that you really need a little gear to get into when your really tired/hurting just to keep going.
I've left the 36t ring as the biggest though so the bike still looks nice
1993 Kona Hei Hei, 2013 Mutiny Robbo X-Sekt, 2006 Rocky Mountain Blizzard, 2007 Mongoose Sabrosa 29er, 2016 Transition Scout, 1998 Mk 1 Standard Trailboss , 2013 Salsa Vaya, Player Special - 2015 Ted James custom roadie