Caesarstone doesn't require sealing. No quartz countertops do. That is one benefit over granite. Amazing that it is the same price as Hi Macs. I'd check out the fabricators you are looking at. Look at their seams, get recommendations. See if they use the phantom seam system, if so you shouldn't really be able to see it. They are almost invisible - especially in lighter colors. Also ask them to use as few seams as possible.
Fabricators have to go with the sink manufacturer's template for the cut out, they have an option of a reveal or no reveal, I think. I'd go with a slight reveal - so you see maybe 1/8" or less of sink edge, that way if it's there - you will remember to clean it. If you go with a negative reveal where you definitely don't see the sink - out of sight out of mind & it will get overlooked & gunky.

Granite Girl,

Sorry for not being clear, the issue that I worry about, the gunk... I wanted to find out more about that.

By putting two pieces of granite, or quartz or whatever together there would be seams. And these seams fail, ie water gets past them? They get mold? They change color?
And, where the countertop meets the backsplash, and where the undermounted sink attaches to the countertop, issues here with gunk, how bad?

Seamless Hi macs or corian, though not as nice... would not have the same issues with gunk.

Sorry for not being clear....

I will look into price some more. Intergrated backsplash costs a lot apparently.

Thanks Mike