Had a real cheap thing from EBA long ago, totally stopped working after a couple of weeks owning it (for literally no reason, nothing happened to it). Next was an X3200 which used to give huge and ridiculous fluctuations in its' readings and made me thing I had gun problems, but I think I was unlucky with that one. Currently got the X3500 and that's worked fine so far, but I'd say a similar thing to the above really; personally if I'm generally playing at sites with a 345 or 350 limit I'll aim for 330 tops, I've seen lots of differences in the chronos at different sites up and down the country.