For all of you more seasoned pu erh veterans out there, in your experience, how much variation is there from the same cakes (at least in name) year to year? For example, if you liked a particular cake from Tea Urchin last year, would you buy the same cake again, sight unseen, this year? If you have done this in the past, how close are they? I know this would depend on the producer. For example, I suspect there might be more variation from Menghai than Yunnan Sourcing. But I don't know... what's been your experience? Big changes or little ones? What factors affect how different a tea would be from year to year? How do you decide whether to purchase the same cake again from the following year's vintage?