I have very little experience with new imaging technology. I have a Simrad Go7 xse with totalscan that I've used one time. My boat came with 2 Lowrance Hook 7 DI that I have removed because I want to setup an ethernet network. I just bought a new gen1 helix 9 si that I got a really good deal on. For the second unit, I'm considering either the Helix 9 mega si or a gen1 Helix 12 si. I can get both new for about the same price. Which would you buy or do you recommend going a different route? I generally bass/crappie fish waters 20 feet or less.