I've used Mears several times, once to get to All Stars. I've never waited more than 20 minutes. The time we were going to All Stars, we waited about 10. Timing depends on how many people have flights arriving at the same time and get to Mears together. We were the only ones getting dropped off at the All Stars, so there was no extra time for checking-in.
I'd gladly use Mears again as they are still cheaper for us at this time (just two people). I've always had great service and reliable service. But when it is cheaper to use a towncar service, we'll switch to that.