Be prepared to do a lot of riding around when you get the side scan. I just about guarantee that your first trips to the lake with it, you will spend more time scanning than you will fishing. Dad and I probably spent our first two trips scanning and never put a hook in the water. The first trip out, we were so into watching the screen, that we weren't really watching where we were going and ran up on a sand bar. LOL.
There's another plus to the bigger screen units that I didn't mention. That being...the bigger the screen, the more you can see by using a wider scan area. For example...the 5" screen units will let you scan the same distance as the big units will. But if you are scanning 100 feet off each side of the boat...well that's 200 feet of stuff on the bottom, that the unit is trying to display on a 5" screen. Actually...it's not even a 5" screen, in the way it displays the images. It's only 5" DIAGONALLY...so by the way the side imaging displays the image...you're really trying to cram 100' off each side into just an inch and a half or so. So you can imagine how SMALL it has to draw stuff trying to fit it on the screen.
To compensate for this, on the small screen units, you must reduce your scan area size....down to around 20-40 feet max. By doing this, you can't cover as big of an area with each pass...but you can actually see what's there and it draws it much larger. If you go to a lot of the forums and look at those guy's images where they are big and crystal clear, etc...you'll notice that they have shrunk the scan area down and rescanned the tree/stump or whatever it is they are wanting to show off. Another way of doing it, is to scan on one side only...that way it utilizes the whole screen to draw. I don't particularly like doing it that way; I think the whole advantage to side scan is to do both sides of the boat at the same time.
There are a few disadvantages to the big screen units though. #1 is the cost. Hard to lay down $2k+ and then worry about somebody stealing it, it going bad, etc. #2 is the sheer size of them and trying to find a place to mount them. #3 is that they still don't come with much of a warranty for such an expensive purchase...especially being an electronic device. Most of them are just a 1 yr warranty. If you buy and register through a BBC sponsor, you get an additional yr's warranty.