Funny stuff! I just got rid of some 4 year old square taper North Shores. In 10 years of racing DH (225# expert) I only broke 3 spindles. 2 were Shimano UN70, one was a UN50. I only replaced them b/c I wasn't sure how much longer they would last and knew that they would go at the worst possible time. Threw on a set of Hone's.
I didn't think you could still find a square BB/crankset. The isis bottom bracket is pretty standard across the board these days. Even my BMX race bike came stock with an isis BB. Come to think of it, I can't remember the last time I had a bike with a squared BB. Either way, if you want to run one, it's all good.