I really like the larger screens. I had one 7 inch screen in the past and two larger ones. The difference resulted in my own eventual upgrade to units with 10 to 12 inch screens, no 7. In my opinion, it's not very effective to use split screen on a small display like the 7. Split screen is a function like having two different windows open on a computer; one can be the chart map, and one can be the sonar, for instance. This is very good to be able to do. Think about going with a 9 inch screen.

The Structure Scan is really worth it. This feature gives you a view that is much more "readable" by the average person as to what he's looking at in the water. Of course, some tweaking is typically required to get it working just right, but it's impressive. This is the main thing that drove me to spend a fortune on new electronics.

I would suggest you look at getting HDS 9 Gen2 Touch. The Touch models (no other) have the structure scan processor built into the main unit. You still need 2 different transducers, but there are "bundle models" for an HDS 9 Gen2 Touch with both transducers so there is nothing else to buy - all in one box. Getting Gen2 saves a bit of $ over the latest greatest Gen3 if the price is stinging. I have no issue with my Gen2 units to this day.

BTW, once you have a single HDS Touch unit, it becomes possible to add other units (even non-Touch models) and share the Structure Scan view with both displays. This is done with a network cable between the two units. The Touch models have an extra connector on the back to allow such a connection and feature. The 9 Touch even has two of those connections.