I LOVE some "bendy" stirrups...HATE others!
LOVE: My old-school Herm Sprengers with only a single joint. Somehow, they are perfect for my body and my knees don't hurt anymore and I never lose an iron!
LIKE: My newer Herm Sprenger System 4. Still alleviate my aching knees, but they seem to feel too "loose" on my foot.
OKAY: Knock-off brand with single joint. Okay, but the rubber cracked within a year.
HATE: Those Korsteel Flex II Irons! http://www.doversaddlery.com/korstee...ons/p/X1-0707/
There's no rubber covering, so when you ride w/o your feet in the irons, they clang around like CRAZY!
If you do decide to spend a pretty penny on some Herm Sprengers (or equivalent), be sure to order the proper size! I tend to like my irons smaller so I don't have too much wiggle room to possibly lose an iron. My snug 4.25" Herm Sprengers have always released my foot during my (many, many) falls though!