My mini griptilian has had two sets of springs replaced. It needs a third, but I haven't sent it in again yet. It chewed through the latest set of springs with very little use, and very few openings and closings, as I barely used the thing for over two years while hospitalized and recovering.
The lifetime warranty is great. Benchmade's service is great. But the knife cost me $69 plus tax, and after the next trip, I'll have spent nearly half that in shipping it to Benchmade. (They've picked up the return shipping.)
Also, the last time they sharpened it for me, which screwed up the edge, which is a PITA to fix on the hard 154CM steel. (They do this as a free courtesy, whenever they service a knife. However, it seems not all of their sharpeners are equally skilled.)
All that said, I'm convinced I just have a weird knife. I haven't found anyone else who has had so many springs blow. I'm not rough on the thing, either, use it for light cutting and don't flick it open or any other nonsense. I do like the lock, and may one day pick up a higher end axis lock knife. For now, I carry a Spyderco Byrd traditional lockback or a Buck Vantage linerlock. I'm not spending any more on fixing my lemon knife. One of these days, I may see if I can find replacement springs and fix it myself.