I wont troll less than .7 mph. Like you said, the action on the hot grubs needs a certain speed to work. If I'm not mistaken you need to be running about 3-4 mph to get clear pictures using side scan. Some people use side scan to find the fish before they start fishing. I use 2-D sonar for that. And I constantly use my sonar when trolling. With maps on your sonar you can watch ahead for shallows coming up along with avoiding any premarked brush piles and with 2-D you will see "new" brush piles as you go over them. Then you need to speed WAY up so your jigs doesn't hang the brush. I hardly ever use down scan.