I've had the 3lb version in for almost a year with no problems. My car sleeps in the garage though - but it's definitely gotten into the 40's or so in there. Never a hitch starting.
Just recently had a problem with it being drained after sitting - to a point where it wouldn't take a charge, but Tony has offered to either charge it on their equipment or give me a deal on upgrading to their new VPH400 model (which is VERY slick - discharge protection circuit, on/off switch, overcharge protection, etc... never come back to a dead battery
.
I'd say they definitely stand behind their products - and Tony's always been very communicative and helpful in emails
