I would go punch some buttons at the stores and then decide which one you like best. I have a HDS 8 and you can have all 4 modes showing at one time but the screens are small and more difficult to get any real info from. I believe you can on the 5 and 7 as well but not definate. Get the LARGEST screen you can afford (or not afford) as the larger screens will show more detail in DI/SI modes. Might consider the Touch version on Lowrance, very easy to change screens and make adjustments.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.