Michael -- you've indicated that you hand-hold all of your macro shots. What is your technique for the MP-E 65? I haven't had much success with mine unless I use a tripod and a focusing rail.
I've never used the MP-E on a tripod and I don't even have a focusing rail. I hold the camera with my right hand and support the lens with my left hand. I try to rest my left hand or elbow on something, e.g. my leg if I kneel or sit in the grass. When shooting insects on flowers or leaves, I often try to hold the flower steady with my left hand while resting the lens on that hand/wrist. When doing that, I try to slowly move or turn the flower to compose the shot. That obviously only works on insects that hold still for a moment (these bees didn't!). Some insects let me grab and move/turn the flower they're sitting on, some won't.
Other than that, I delete lots of OOF shots