I keep hearing the Peacock irons are not suitable for heavier riders. I have a set on one of my saddles and have never had a problem (I am heavier) I have never lost a set of bands either. They were expensive ones though, not the cheapies.
Having said that I prefer the bent leg ones, you can get away with using them for showing.
Also when buying a saddle I always check that the leather will pull off the bar in an emergency, some are better at doing this than others.
I once had an accident where my mare reared and went over sideways on the road, we landed with me still sitting on her. Her weight crushed the stirrup around my foot. She got up and set off home dragging me, luckily after two strides the leather came off the saddle otherwise I would have been dragged for 2 miles on the road. In these circumstances I doubt the bent leg would have helped but the peacock might.