Playing alto 2 ⅓ years
Interesting, thanks! As it happens, they're out of stock at the moment, but I did order one out of curiosity. I have played Vandoren 2, 2 1/2 and 3. What's funny is that Plasticover, which I like for some things is very comfortable in a 3. I occasionally try a Vandoren 2, but mostly play 2 1/2. On my cheap soprano, I use 2.What I can tell for sure is that the Monster #3 feels between a #2.5 and #3 with the last kind of reeds I played: Alexander NY (I am saying this so that maybe someone else can pitch in if they know these reeds).
In my (short) experience, the Vandoren are the hardest reeds I ever tried.