I umpire JV, Varsity, and Legion (Junior and Senior). I moved to the Enduro from my AS Cobalt CP and have not regretted it a single time. It feels slimmer, and I haven't felt anything when invariably the F2 in front of me doesn't do his job. A peer of mine who does JuCo ended up getting one and he loves it (he moved to the Enduro from the Gold W as well)--told me he took a 90+ mph fast ball off the shoulder and didn't feel it.
I don't have any experience with the Mk2, so can't really provide any feedback there.