So... I took this deck to my LGS for Commander League and I have to say it performs well. I built it to be a "fair deck" so I won't loose points for excessive combo, excessive searching (doesn't include fetch land searches in my CL), excessive land destruction or drawing too many cards/turn (Grenzo's ability happily gets around that rule). Also, the 30 lands worked very well. I've now played a total of 13 games without the need for a mulligan.
If the CMC of cards is low enough and there are a few other ways to generate mana, there's no need 35+ lands in Commander. Also, I am running a lot of Fetch Lands and with
Crucible of Worlds, 1 Fetch in my GY pretty much allows me to thin all the lands out of the deck which, makes Grenzo's ability that much stronger!
Crimsonking, I think you'd get more out of your build if you add more fetch lands. Also consider that anytime Grenzo shits a sorcery, instant, artifact or enchantment to the GY, you can move it under the deck and then use a fetch to shuffle--effectively giving yourself a second shot at that particular card.