Twice I've had a little button break off the spring clip inside a chinook cup, both times I discovered it while derigging -- the other button was holding the rig on 
I quite like the idea of having to have two bits fail in the same session before you lose the rig 
NotWal, they are now a socket head capscrew that looks fatter M5 vs M4 (?) but having said that, I never broke the old ones. I've had 10 y/0 ones I refurbushed and the bolts thru the tendons may have been bend a little but never broken. I think the thin stainless sleeve in the tendon helps a lot.
Nebbs, I had the same thing with cups all the time and that is why I changed away from them. Pretty scary when you've had a big big sesh and come in to find one of the button sheared off the spring clip thingo
I have sailed only Euro pins now for many years. I only use Bodge rubber PJ's. Can't stand the tendon things, too long and stiff and I don't trust them.
I don't do much wave sailing these days but I do sail a lot of hours. I have only broken one pin and it was on the first sail on a brand new one. Careful examination after revealed that the pin had been done up too tight into the PJ, twisting the threaded part and and fatiguing the metal. It was already broken part way through. Now I buy the parts separately and put them together myself. No more issues. :-)
Food for thought though.... some sort of easy fitted and released safety rope/strap between the board and the rig would be a good idea for any type of base.......
(1) Boge joint: if the rubber breaks, how do u know the nylon safety strap is intact? A lot of it is hidden where it wrapsaround the top and bottom of the rubber hourglass thing
At least with a tendon, the safety system is a downhaul rope you can see
(2) Roger, your example of a broken off pin can't happen with the Chinook system, as I said above the pin and the cup the tendon goes into are one peice.
(3) strap between board and rig? the Chinook europin base is ideal. The onlything that can break is the tendon. Theyare obvious when they are about to break (as a poster above said)..... at any rate replace the tendon every 2 yrs and you're fine! If tendon breaks, the failsafe is a piece of downhaul rope that is a strong as you'll find.
I use the cup style now because my mast detached in swell and it too a while and was awfully awkword to get kit back together.
I wont ever use this pin style again.
