I saw the topic and told JH he otta chime in on the OV-1 since I knew he had Mohawk time. We had the same seat, ESCAPAC, in the S-3's. Biggest thing we had drummed into us was keep your thighs flat on the seat pan. Based on info from previous ejections just a half inch of clearance could snap your femur like a toothpick. Going thru the canopy wasn't the problem. Shoot, we had a input tray across our laps that was a much bigger concern!
On the Intruder, originally crews were to jettison the canopy then punch out. Problem was the canopy wouldn't blow clean. Instead it came about half way back and crews were nailing the front of it. So, they basically said screw it we'll just go thru the plexiglass instead of plexi and metal. Prowler's have a different canopy and haven't had the same problems.
Have to admit, punching out of a helo just doesn't sound like much fun.