I wouldnt say ER10 is supposed to be the very best of BTs low-rye whiskey.
I said that a bit unclearly. What I meant is that ER10 is supposed to be the best 10 year expression on BT's low-rye mash bill stuff in something that isn't a cask strength.
Taste is definitely a personal thing, but I get a almost menthol flavor in the finish of the newer bottles of ER10 that I don't find in the older bottles.
It is barrel select, but part of using more 10 year stuff also meant using barrels from a larger portion of the rackhouse, and that can make a difference.