Hi, sorry to hear about the ribs, its a bugger, don't watch a comedy, or eat a curry.
I have always used seat harnesses, and occasionally tried waist upon the insistence of friends.
I cannot get into waist harnies. On the wedgie issue, I find it helps to practice the Sumo Sack-suck exercise where you pull your nuts up into your throat, then you can kite without a crush...
Kidding, I used to have wedgies with my first kite that was trimmed all wrong, and had a huge range on the bar, this resulted in a poo stance, and a wedgie never let it out. Since I have ridden Edges, my stance is way more laid back, and I now use the NP seat harness, constant tricks, loops, jumps, and never wedge to be seen.
I have thought about it and my opinion as an older rider is that we as hominids have evolved to perambulate, run, jump, climb and a multitude of other activities based upon the pelvis being the place where the legs power, shock, and weight is distributed into the torso by the entire package of muscle sinew bone, and cartilage. With a seat harness this is a continuation, but with a waist harness, a lot of those movements, and shocks are taken by the lumbar region of the spine, actions that it never evolved to encounter......I dare say that a lot of waist harness kiters who are active, might find that they have lower back problems later in life, or possibly have great muscle tone and avoid some problems, time will tell, but to me a sit harness is the way to go.