I have an HDS-10 with structure and side scan. When I first got it, the first day out it messed up after a couple of hours of searching bottom with it. Called the next day and they sent me a new structure scan sonar but it did not fix the problem. Called again and got a new structure scan box which did fix the problem. All was good for about 6 months then the screen went white while in FL fishing. Called got and RA and when I removed it I could hear water in it so the seal was not good. It was flush mounted under my T-Top so not subjected to water at all, other than washing boat. They replaced it with a new one and while talking to them it was somehow an old very first edition one even though I had just bought it but I bought it online from cheapest place possible. (go figure)
Even though I did have some problems with it customer service was very good for me, no complaints what so ever. I have called in twice for tech support on how to do something and both times they were eager to help and helped very quickly. I have read many posts about bad service but of the 6 times total called had zero issues or long hold times.
When the first sonar did not fix the problem I needed the fix very quickly since I was leaving for FL. and they overnighted it to me. I didn't throw a fit or anything like that, just told her how bad I needed it and didn't have time to send the sonar back first. She said OK and overnighted it to me even though I had 3 days, she said incase it did not fix the problem they would have another day to fix the problem before I went. Was very happy with that service.
With all that being said after seeing different pics online I think the HB has clearer side imagine pics than Lowrance. But in the gulf looking for structure or sunken items it works flawlessly. A lot of times GPS points are close but not right on, you have to do some looking around for it and the sidescan makes it so much easier. I have a Raymarine C120 as well and use the side scan for Lowrance a lot. I fished in Destin a couple weeks ago out of a friends boat and he had a C120 as well and searching for points with that only and not in conjunction with sidescan made it much more difficult, I guess having both has me spoiled.
Either way you go a bigger screen is better for sure.
If you want to see one in action come on down to Lake Cumberland and I will give you a demo any time.