Anytime you hook your toes/instep into a toe loop or toe bar you create the potential for a sprain or break. Most of the time I don't hook in but rather I brace(push off of both bars with a flat foot) into a high-back, non-folding seat. When I'm in something really nasty I will hook in as an injury is more desirable than getting separated from the boat. I used to like toe loops but found that I would rather brace from a higher point than a lower point. With toe loops I felt like I was pushing myself up and out of the seat rather than back into it. I built a frame with a standard double bar, as opposed to toe loops which are braced from farther down in the frame. I also did not brace the foot and toe bar together, so I could high-side to either side of the cockpit in big water without having to unhook my feet. For the spacing I ended up settling around 3.25'' inside as a quarter inch either way felt too tight or too loose. A friend of mine runs closer to 3.75 or 4'' and he tells a story of how he was surfing with his body out of the cockpit and his foot stuck through the bars. He said he pulled the boat on top of himself and flipped on purpose because he thought he was going to break his ankle. When I see double bars that are too far apart I cringe a little and I usually say something to try to get people thinking before they have an accident. Either way, if he would have been in dangerous water he could have died. I suppose he should have never been out of the cockpit anyway. I ended up removing my perimeter grab line this season to remind me to stay inside the boat when I flip.
Most frames have hazards. The prototype I built has 8 of them, which are the 90 degree angles created from the vertical drops and braces. At this time I don't feel the frame is safe enough for class 5 and it has only seen water once, lower 5 NF payette. I will not run any other part of that river until I fix those hazards and I probably shouldn't run it at all for now. Ron McClay builds some of the safest frames I have seen, but the towers he uses are not strong enough for my liking. Every cataraft frame with vertical drops(NRS, rectec, etc.) that have not been properly thought out and designed is hazardous. As far as having a frame with radically curved or angled drop rails, if you can get a foot in there that's a red flag. If the frame is run down big water there's a chance for disaster, especially if the water demands you stay with your boat. If you are out of the seat but in your frame, upright or down, you do not want to be stuck. You want to be able to move around through the cockpit square. I get concerned when I see people scared to flip or praying that it doesn't happen. Every cat boater running challenging water should be prepared at any time to:
1 - drop the oars, brace into the cockpit and hold on
2 - swim through the cockpit after a flip which means running no floor in the rowing compartment
3 - get your head above water and scout down river
4 - make the decision to continue to hang on tight, or reflip(if you have an efficient reflip system and combat roll)
5 - re-enter the cockpit via swimhole and find the oars when you're back in the seat
If you are unable to reflip ride it out, or if you have an opportunity to leave the boat in calm water, get to the shore if it no longer makes sense for you to remain in the river. As a hilarious and highly skilled boater once told me, "at the very least turn your boat over in some flat water and start spending some time on the underside of your frame so you don't feel like you're walking on the moon." Devise a reflip system that is safe, fast and efficient, and learn to use it under all conditions. Alleviate unnecessary hazards and minimize the others. Train your body and mind to be ready for any possibility. Wear as much safety gear as you can comfortably and safely deal with. Don't hope that you stay upright, be ready for your next flip. Don't worry about breaking your fancy expensive gear. If you don't want to spend extra money, build something that you can fix yourself when you break it.