Nope. I tried 33# one time and it was . . . rough. The most I am willing to put in is 28#, and it is a really thick mash. Sparging is also a PITA when the MLT is so full.
Yeah I tried 33 lbs one time not thinking that doubling the recipe would provide too much grain. Ended up with 30 pound in there but flooded the mash tun once. Beer ended up fantastic.
Yep, I'm thinking of doing a partial mash with extract for a stout due to my small mash tun. As long as most of the GB is grain, it won't hugely affect the beer.