The ESC is sort of "AA" ball of racing series. Maybe AAA, since the US doesn't really have strong national series for DH, enduro or even XC. So while the ESC and MASS events at the same venues pretty much run on the same courses, many of the ESC racers do seem to take things a bit more seriously.
A MASS event at Glen Park or Blue Mtn would be good starter events, based on my experiences racing at both venues. I've ridden at most of the other venues listed, but only raced DH at a couple.
Unfortunately, while my shoulder is allowing me to ride aggressive terrain again, I have a lot of recovery training and overall fitness increases to make before I can race again and have the experience be fun. I still can't decide between DH and enduro. While I do enjoy enduro, there is just something about the intensity of DH racing and the need to get one course absolutely down.
