<font color="blue"> dual hydro drive </font> is just a fancy way of saying "consumer style drives"; as opposed to pumps/wheel motors.
The Toro Z (from their website last year; didn't see any changes just now though) and CC RZT will have the smallest grade of that tranny. The ZX transmissions will be more like the CC Z-Force (still integrated, but rated heavier).
If it's an '06; I'd gladly take the RZT's Kaw as easially as a Honda. I still wonder if they'll try sneaking cheaper components into it (knowing they're going into consumer machines), but then the same paranoia could be said about Honda or anyone!
Now that I've thoroughly confused you; the good news. /forums/images/graemlins/crazy.gifYour size of lot is what those things are designed for and should give you many happy years of service with either.
Of course, if either mower brand or engine brand is preferable to you, you might be more likely to maintain it properly so perhaps some consideration there! /forums/images/graemlins/grin.gif