Fair comment PureCountry - there is no one size fits all solution. I enjoy debating these things though as others experiences can make you look again at how you do things.
Arthritis has always been my biggest cause of old cows being shipped across many breeds and many years. The wet climate in Scotland caused far greater rates of arthritis than we see in Canada though.
Interesting about the teeth and short grass conditions - I wonder if it is really the sand or short, hard grass that wears the teeth or if it is the mineral and soil type under these grasses that causes the teeth to be more susceptible to wear?
I bought a bunch of 40 commercial red Angus type cows at a dispersal back in 2001 that were at a minimum coming 4th calvers, we still have 7 of them left who will be 13 this spring. We actually had 17 left only a couple of years ago so for 17/40 to reach 11 that is fair longevity in my book. The culls have been about 50% open/50% with arthritis. They were a real good buy as they had been run tough before I got them and I think that had weeded out a lot of the poorer types and also got them past their 1st and 2nd calvings when a lot seem to fail to re-breed.