For your original question: down imaging is better than chirp if you have to choose. Down imaging shows a superior image, you can spot individual fish, trees, brush piles, rocks, etc. With traditional sonar all (chirp or not) of that looks like a blob, so you have to fish it to figure out what you're seeing.
You can download free maps for Lowrance products at https://www.genesismaps.com/ and they are SUPERIOR to the maps you spend $100. Goto that sight and see if your lakes have a map available for download. After finding these community generated maps I'll never spend money on a map chip again. You might need to call Lowrance customer support to get an answer on Hook2 support for these maps as the website is lacking details.
I'd say if the Hook2 doesn't support the C-Map Genesis maps, don't get it. Spend a little more money to get one with free downloadable map support.
I know you don't want to hear this, but I went the route of "buy cheap" and after learning a lot about fish finders, I realized that was a mistake. The unit you really would be happy with is the Lowrance Elite-5 TI, but it's expensive. However, it's a buy once fish finder, versus buying a Hook2, realizing all it's limitations, and then buying the unit you really needed later on.