Based on what you want to do, fast cruising without WOT much if at all, I wonder if you should have stayed with an upgraded Bravo1 that would drive deeper and have less slip, rather than the Imco. Then again maybe it wouldn't handle the hp you are putting out.
I haven't crashed, but 2 things come to mind. My old '63 inboard, which maybe hits 40 at wot, has a tendency to dig the bow into waves at high speed, will toss you across the seat or against the gunwale depending on which direction, hard. I know people who have broken ribs. And jet boats, if you lose power at high speed, will swap ends quickly, nothing in the water to keep the stern behind you and a 600 lb engine wanting to move to the front at the same time.