My team and I have been testing Menendian's list for a couple of days and Oblivion Stone really shines.

We are still deciding to include B.Ring, but we added Extirpates in the sideas well as maindeck bayou.
The maindecked Crucible is very good. We play no Smokestacks, but additional 2x Stone (1 maindeck + 2 side).

As for Urborg, is that better than riftstone portal? okay west for urborg is far better, but portal can save you from moon effects and ee away em while urborg not (or yes? i'm not sure 'bout that one.) Then we dont need oblivion stone.
We finally added Portal and removed a basic forest (now we only play 1) and it's worked okay. Under a Moon effect, if you have Portal in the yard, your Mountains produce R, G or W... that's awesome and makes Rau of Revelation flashback easier to cast.

Aggro needs to be very fast to defeat this deck, counterbalance is easier thanks to crucible, EE, Stone... and combo... well... you cannot beat everything i guess....