I have been using a 70D for the last few months. I find it to be really enjoyable to use in a Sea and Sea Housing and compact with the Tokina 10-17 mm Dome Port. Just don't even know where to begin when making the comparison to a G1X. Totally different experience. You may want to rent a couple of different setups before buying. I can vouch for the 70D and would Recommend the Sea and Sea and or the Nauticam housing with the 10-17 or a 100 mm Macro .