I know HB does not offer an extended warranty. But some retailers do offer them on HB units, so depends on where you buy it.
Now that Lowrance finally has side imaging, or whatever they named it, things are more even between them and HB. That was a huge plus to the HB's over the Low for the last 4-5 years. Some say the Low's have better 2d, but HB has released some software updates lately that seem to put them at least on the same level. So hard to go wrong with either functionally speaking.
I was all set on a HDS last spring. But after being told the same horror stories of returned defective units at 2 Bass Pro's and a Cabela's, I forced myself to look at HB harder. I also heard about the horrible customer service rep at Lowrance from all over the net, which was added reason to look elsewhere. HB has outstanding customer support with many of their employees helping out on several forums on the net. Everytime I've called, I got right through and got the help I needed. So night and day different from what you hear about from Lowrance that saying night and day isn't sufficient. HB also has free software upgrades fairly often to add new features, correct or fine tune others, etc. Add the lower overall price, at least if you're looking at getting the side and down imaging units, and it was a no brainer in the end. I ended up with a 798CI SI and 997C SI.
I've heard Lowrance is finally getting on top of the HDS problems, and I'm sure they're great units. But I just can't see spending the same or more money on them when their customer service is rated so, so poorly. When I spend that kind of money, I expect top notch customer service.