I've had no bad luck, but mine are old models.
Bigger companies seem to sometimes make it cheaper over time, smaller ones sometimes make it better (to get to be a bigger company; like Everlast). So maybe the old HF ones were stronger. But I've had great luck with the old ones I have. The backup is like a year old $9.99 one (not good). Well, the Hitachi ones will be here before the old ones break on me
Thanks also, I used two of the coupons today. I only have 20% ones in the wallet.