We have those for our paddle rafts. Not at all durable, that said they get fhe job done and I like the way they paddle, unlile the Warner guide stick. Ive roached a dozen or more in five years of guiding. Mostly severely bent or snapped while surfing full rafts. Im also 6'3" and 270 lbs so its not hard to break shit. I always used the 60". We give that size to everybody from little kids to folks my height, so that size is more universal. Also the 66" is easier to break because of the increased leverage.
On a day trip every full raft has two spares, so buy a few extra.