I have just under an acre of mostly level grass to cut.
Hi, I was in a a similar situation wondering what to get for my lawn. (I have just under an acre as well.) Earlier this spring, I wound up buying the Toro Titan MX4800 (like the ZX, but with wider tires and a suspension seat)
I used to use a push mower that took me hours to mow. I gave that up and had a contractor mow my lawn for a couple of years. But, I was never really happy with two things: 1) The timing of when it was mowed to coordinate watering and fertilizer treatments, and 2) the quality of the job. Now mowing it by myself this season, I have the best looking lawn in the neighborhood! I mow it when I want with hardly any effort and time. I find it a joy now! It is actually fun to do and I find it to be a major stress reliever from my hectic day job. It was worth the extra money for me.
Mine doesn't smoke at startup. I wonder if you are using too much choke? If it's hot outside, I found that the choke is not even needed. If it's cold, I just pull it up half way and then push it back down after a few seconds of starting. Also, I put the throttle at half way when turning the ignition.
I haven't paid close attention to gas usage, but the rule of thumb that I've been using seems to be holding true where I get at least 5 hours per tank.
I hope you enjoy your Toro as well!