I smoke a good bit of Embarcadero. I was given some with about three years of age on it (probably on the heavy side of an ounce). My palette can't hold a candle to Kyle's, but I'll throw a few observations out there:
--Yak is right, it get's a bit sweeter. Still, while the change in sweetness is noticeable, it's not so much that it changes the overall experience of the VA.
--It behaves like most blends do with age - everything rounds out a bit. For me, this did take away from things a bit...one of my favorite things about Embarcadero is that, even fresh, it's incredibly well rounded and nuanced, so without sharp edges to round off, it sort of homogenized things a bit...if that makes any sense.
--I wouldn't go as far as to say that age makes the blend monotonous, but it tames the unpredictable transitions between Virginia and Izmir level out a bit. For me that's kind of a downer; if you prefer a more consistent smoke from beginning to end, this might be nirvana in a bowl.
I have no idea what more than three years would do to it, but I don't know that I, personally, would want to find out. Don't take this to mean that aged Embarcadero is bad in any way. It's still quite good...my preferences lean towards something under a year old, though.