There is a problem with having dates on the shirt, namely that in a few years the shirt will become, well, dated. If someone were going to wear the shirt only for certain occasions (e.g., for fan conventions), the shirt might remain in good condition for several years.
Having said that, I hasten to add that my own opinion here shouldn't matter, since I plan to try bidding on an auction or two and if (as I suspect) I am outbid, then just giving a straight-forward donation to the site; I don't plan to buy any swag. I'm only throwing this out here because I suspect that putting dates on the shirt might limit the number of people who will decide to get them.
Joy,
Lynn
