I've found my HDS to be an extremely valuable and useful in finding bait and stripers.

First, you need to understand Lowrance and Hummingbird both have similar technologies but each has their distinct advantages over the other. The names of those technologies are very telling and provides a huge hint at some of the differences. Hummingbird has side imaging while Lowrance has structure scan. Side Imaging echos straight down then echos to the side both left and right. If something causes an early return then the echo can not see on the other side so that is displayed as a shadow on the floor. With this, it's easy to see a school of fish or bait that are suspended and you can even get an idea of the depth by how far away the shadow on the floor is from the mark. Side imaging does not have a dedicated down imaging transducer but used information from the sides to simulate a down image. The 360 feature extends this "side imaging" to a single transducer that rotates under the boat that sweeps all the way around in a 300 ft circle. Lowrance's Structure scan is primarily designed to return structure information in two ways. One, is a dedicated transducer to each side, then they also have a dedicated transducer straight down. Structure scan CAN and DOES return information on suspended bait or fish, but does not show a shadow behind it on the floor to help figure depth. The advantage of the HDS is in the down imaging and the networking capabilities in MY opinion

My experience with my HDS has been much different than Justin's. If you are scanning a creek that is 400 ft wide, the bottom should be dark with a gradual increase in lighter color. If I see patches of white in the middle, I know that is either bait, a large school or both. I can then move to that side and find that patch. I can even move the cursor to it and mark a way point, then find that way point on the GPS. I can then go over that patch and the combination down scan and standard transducer can tell me exactly what it is. I can then see the depth, and I can see at what depth the creek is. The down scan on the HDS has some huge advantages over my old Lowrance unit. First, you can overlay the down-scan and standard transducer which gives the head twice the amount of information about what it has scanned. Bait shows as bait, schools of fish show as schools of fish and trees, brush rocks show as trees brush and rocks. Then, the down scan is capable of figuring out the difference between humps on the bottom and fish. I can now see the difference between two or three stripers just off the bottom or a hump. Those fish are usually inactive, but if you bounce a bait in front of them, they will usually eat it. I've picked up many fish due to now seeing those fish and sitting over top of them reeling bait up through them.

Where I would agree with Justin is if you are scanning a flat or shallow water with the HDS. It will show you the structure but it won't be able to distinguish between a school of bait or brush to the side. The down scan area is smaller so the sample is smaller. I can't tell you how the Hummingbird would do but I would think it would be similar but slightly better due to the shadow technology.