Now that I've worn out one sprocket, somewhere around 7500 miles, third since you ask, I now need to replace the other six as well! The only problem I have is which HG to buy.
Should I go cheap and get HG30, mid range with HG50 or top of the shop HG70? Given that they all end in 28 teeth and start with either 11 or 12 just what is the difference between them? Is the HG70 lighter than the others or does the HG30 come with chocolate teeth?
The original cassette was HG50 and the current worn one is HG70, it doesn't seem to have lasted as long as the 50.