Absolutely NO idea if you can use them in tourney's. Yes my cousin and a number of my friends have them in Minnesota. At first we got them so we could see what we were fishing as far as structure, weedlines, etc... while ice fishing. If you are standing (and yes, driving) on 36 inches of ice and you cut a 16 in hole in it, the camera works phenomonally well and is a favorite with the kids and anyone who hasn't ever had the opportunity to see one in action.
We later "figured out" like it was an epiphany - that we could use them in the summer. It really helped us better mark our GPS spots and also see what was down there. My 10 and 12 yr old boys would rather you catch the fish and they watch the screen to see them bite! But my Dad gets "all fired up" when he saw us pull it out on a deep point to see where they were hangin'. He thought it to be an unfair advantage. I think they rock. But you can wind up carrying a battery and cables. It's always a pain to have one more battery and more "stuff" that you have to have all the pieces to. If you can spring for it and are curious to see what you are fishing. Go for it. Though I must say, I have fished here for 6 mos without one and haven't even missed having one in the boat. But it would be good to find some great deep water structure on that river...