I've known quite a few people that have taken them. They're natural guys wanting that "competitive edge" without having to take steroids.
One guy who semi-frequented my gym started taking them and wouldn't shut up about them, as he had gained 15 pounds or so in the last month. The thing is, in that time he cleaned up his diet big time, working on his pre-intra-post workout nutrition, and started training harder than I had seen him train previously.
Could it have been the SARMS? Possibly. Could it have been the fact that he actually started training and living like a strength athlete? More likely.
So to wrap this up, I've never taken them, and considering I'm natty now after 3+ years of on and off usage, and have pretty much lost everything I had gained previously, I still wouldn't take that shit.
P.S. oly lifters shouldn't be taking SARMS or anything like it. You guys lift in tested feds, and even if it could possibly give you a very slight advantage, it's against the rules, don't be a bitch.