if you seriously want to cut down on mowing time, get a 60 or 70" deck and call it a day, they are pricey, but if you buy a used commerical mower then it will still last forever. my parents bought a brand new 729 grasshopper and then they got a used one from Evolution Ag, I can't even tell you which one is which, but i know they saved about $4k on the used one just by buying one with a "couple" hours on it.
Edit: Buy this, kubota 3 cyl liquid cooled will run forever if you take care of it.
http://www.evolutionagllc.com/equipment.asp#/?fsucriteria=;category=Riding%20Mowers;page=1;items=20;sort=0;wid=1;disposition=used&fsuid=35042712-11ee-448c-884b-c70438576cf1