All good info, and I'll second what Bman said: I have a couple of OPD 5lb tanks, and I haven't had any trouble getting my tanks filled, regardless of age. The guys filling them at U-Haul simply never look at the dates. I'd be worried about them potentially leaking, but all of them are kept outside.
One thing you might watch out for, though: some of the tank filling dudes are pretty green, so you should keep an eye out that they don't put more than about a gallon of gas into the tank. I've had one overfilled once, and it was impossible to turn off the flame.
And I hear you, cbpeck, about wanting a good SS if you're going to get one, but remember that you will likely see another come around again. Kettle karma has a way of working like that. But on the whole, try not to worry too much about igniters and the like, which are easy to fix/replace. Make sure you've got a good solid frame and no rust. I've seen a few SSs that suffered some serious degregdation on the lower end with rusty frame tubes and star nuts, and fixing them didn't bring about the greatest results. You also might want to peek underneath both stainless steel table sections, as the crossmembers on the frames can get pretty rusty under there.