One thing you aren't looking at is ease of training of the LAWN MONKEY. You can train a monkey to run a push mower (21, 25, 26 or 30) easily, however running a belt or hydro large mower 32+ takes the right person and time. Of which sometimes you can't find for a reasonable price.
With Labor being one of the largest expense the 30 can really cut labor costs.
I just got a used Toro 40 belt drive with pistols. It was that or an Exmark 30. Compared to the 30 Exmark, the Toro is a ***** to drive but the cut is simply superb. That cant be said for the 30 inch and thats why I bought the Turboforce deck. For me the stripes need to be there or the cut just isnt good enough to charge for.