I just upgraded to a new to me 2006 Lund 1800 Fisherman. The boat boat is showroom new but came with outdated electronics so I am looking to upgrade. I just sold my old boat with a Helix 7 DI no Mega but have become accustom to the unit so I want to stick with the same! So I am looking for advice from any current Helix mega users. I fish the "D" river and BB for Walters and convicts. Do I need the SI or is the DI sufficient. I am not afraid of the extra cost, but only want to by something that is beneficial to what and where i fish. Does anyone have any advice? Thanks!!