I have two McMurray red stars aged 7 years now. They are fine, obviously. I have never had an egg bound chicken.
As far as small bodies, I would characterize mine as average in size though some are a bit larger than others vice versa. I have ten red star pullets just coming into lay now. They were hatched the second week of October.
My Red Stars are roughly 2 now and have never shown signs of distress when it comes to laying. The quality of their eggs has dropped off, the shells have gotten very thin in some cases, shell-less eggs are more frequent, but nobody has ever been egg bound.