Less water is related to survivability of Zoysia. If you want it to look great all the time, I agree, it takes a similar amount of water.
Also, I find it takes more like 3-4 lbs / 1000 sq-ft of nitrogen spring and summer. I can't make it look as good as SA off the 2 lbs recommended.
Weedeating is far less with Zoysia since it doesn't run which can be an advantage. It will pop up in flowerbeds however.
I also believe Zoysia is less healthy and doesn't look as good as SA when mowed above 2" because it is so thick. It does take 2-3 years to thicken up. Mine was thin and whispy until year 3. SA lawns near me look better in April-mid June, but mid-June thru October the Zoysia appears much better because so many are trying to fight off SA diseases that don't seem to affect my Zoysia.
I would take it over regular SA any day... unless compared to Floritam SA... in which case I'd call it a wash.
Here are a few pics. I just fertilized yesterday... so it is still very much in transition from being dormant.
You can see the trails the dog made along with a close up pic... it is rather amazing that after 5 years, the Zoysia hasn't given way to dirt / mud.
One more photo... this is where our yard with Zoysia and the neighbor's with SA meet. The SA is way ahead of the Zoysia right now in terms of growth. The mowing schedule for Zoysia is about 1 month delayed to SA.