For my needs DI is of no benefit. I rarely fish deeper than 15 foot, but at most over 40 foot deep. For the northern deeper lakes and definitely offshore saltwater it is way to go. SI is a benefit when scouting and looking for beds. I will always have SI on my boat. I primarily use my 2D to get over structure and see the depths of fish. I also use the Switchfire Mode to see baits when vertical fishing.