I use the kimura counter to the single leg all the time in both mma and bjj. I only compete in bjj, and I've used it to score many times, including in my last tournament a few months ago.
I use the kimura really just from everywhere, in no small part due to watching Sakuraba. Sometimes you get suplexed, but if you keep the grip, you can just keep threatening. Watch Sakuraba taught me that. lol. Man, I've held on to dwl control, been tossed, stood up, been tossed, stood up, hit my takedown. That control is powerful if you use it well.