Not sure how much this will help you, but here is my two cents.
I had, until recently, a 597ci HD DI on the dash and that was it. The DI is really nice when split with the sonar, but on a 5" screen that means no maps.
Long story short (no pun intended) there was a short in the boat and melted down EVERYTHING including the engine harness ($500 part!). PSA: MAKE SURE your connections are tight to the battery, no wingnuts!
I decided to upgrade when the boat melted down as they were running all new wiring. I wanted the Helix 10 Mega, but that was out of my price range.
I went with a Helix 10 SI/DI Gen1 on the dash, along with a Helix 7 CHIRP for sonar and mapping, also on the dash. I typically run the 10 with a 60/40 (SI-DI respectively) for imaging and the 7 I split sonar with mapping 50/50. I use this setup while trolling. I also added a Helix 7 CHIRP DI to the bow mount as well.
I obviously don't know what you have now, but anything will likely be an upgrade. Get the biggest screen you can afford. Money being no object I'd have 10's all around (as well a Ranger 621, but I digress)
It's amazing what you can see with the CHIRP and SI/DI - Even G1. There is a learning curve (I'm nowhere close yet), but watch as many youtube videos as you can to get a starting point and fine tune from there.
There are literally hundreds of settings, so it'll take some time, but I think it's worth it.
The photo I attached is of a loon that was near the boat. I had one a day prior grab a jointed believer. Thankfully it let go. This one I tried yelling, waving my arms, etc and it dove, but it dove and the electronics picked it up perfectly.