You guys are shooting yourselves in the foot dumbing yourselves down trying to stay small in the deck size department, the size of the job is where you need to start small and work your way up but not when it comes to deck size, here the bigger the better, no f'ing around in this department. Dang three foot decks are a joke, maybe as a specialty machine for certain odd jobs but never for a main line mower.
I would never buy a Wb with anything smaller than a 40" deck, that's the absolute smallest Walk Behind I would ever throw thousands of hard-earned dollars at and I'd really prefer a 44" to 48" or so, what are we trying to do here, they hardly cost more, want to waste money or get the job done?
As for Ztr's the same thing applies, you want to get the job done, I wouldn't get nothing smaller than a 52" and I'd really prefer a 60"
You're spending 8 or 10 thousand dollars and you want a "small" deck?
Don't kid yourself, for that kind of money I'd get a mower that can tackle some GRASS!