Honestly, most of the time I don't use it, but the few times I break down, I regret that decision. What I find with mountain biking, is that as long I'm riding, I don't have an issue with the bugs. It's when I get a flat/mechanical or have to push a hill that it gets bad.

So, as long as you keep moving, they won't bother you. If you're still new to the sport and have to push climbs or take breaks, be sure to use the stuff.

I haven't tried the ones you posted about, but I have tried the Burts Bees repellent. I was satisfied with the results. It may not be a great as OFF, but it got the job done and wasn't as horrible smelling and full of chemicals as the other stuff.

I've heard of people using other Kiss My Face products and been very satisfied. Haven't heard anything about the repellent though.