I will have to disagree with the others that say go with the biggest you can for the $$. I have an 8 at the console and a 7 that I move from the bow to transom based on how I am fishing. But for me, the one thing that I dislike about the split screen is that I frequently want to change the split screen layout from 2 screens to 3 screens etc. And while I am in the menu switching, you might miss something on the sonar etc. So I could leave it in the 3 screen mode, but then two of the screens are smaller than what I would see with two ‘5s side by side. So I guess what I am saying is that I should have considered a 7 and a 5 for the console or 2 5’s. Not that it would have made it better, as the 8 is still an awesome set up, or that I would have gone dual units at the console route. But I never even considered it because everyone said to go with the biggest single unit I could afford.
The built in lake info is overkill unless you are going to be fishing many out of state waters. I would save the $$ on the insight maps and get a lakemaster chip instead. WAY better in my opinion.
The 83/200 transducer is what you need.