I have the old one with the old battery, which has been faultless for a year in snow, rain, etc. As others have noted waterproof the battery for extra protection (I used gaffer tape and clingfilm).
I also have the new old one (i.e. new battery and old head unit – although the old head unit has clearly been changed a bit – it’s got different status LED modes for one thing – I presume it’s got the internals from the silver one). I’ve only used it twice so far, but it seems fine and i’ve no reason to think it won’t last as well as the first one has.
For the price I can’t recommend them high enough, to be perfectly honest i can’t see why anyone would buy anything else. They work, they’re well made, they’re bright, and they’re cheap.