i had them on my fz6 and now on my ninja. when you get them just take an allen wrench and tighten up the adjuster bolts and you should never have any issues.
I know what you mean (bolts are a bit loose from factory), but there was a video on youtube showing how the levers slipped on adjustment detents. It wasn't related to how tight or loose the bolts were.
It's a valid concern. Anyone with these levers.. make sure the bolts are properly tightened and then give both levers a good hard squeeze and make sure they don't slip.
I've had 2 sets for combined ~30k, no issues.