I'm not fond of the 810e's made between 2000 and 2006. They are darker on the treble than cabs before or after. That's about the only thing that bothers me about any 810e's. Pretty much all the old SLM-made Ampeg cabs until 2006 were made with OSB instead of plywood, too, but I sure see a lot of them still in service and holding up just fine, so I'm a little less freaked out about that than I used to be when I found out

But still, I think the best 810e's are the ones being made by LOUD over the past few years. Made of plywood and the treble's brighter.
www.unofficialampeg.com/dating.html tells you how to date the SLM-made cabs. Basically it's the 5th digit of the serial corresponding to a year this way:
A = 88
B = 89
C = 90
etc.