$3,000 is not top of the line rider. John Deere has 300 and 500 series riders that are double that. They have 4 wheel steering and 4wd models and a whole mess of configurations and options.
I think you are putting the cart in front of the horse. It appears that you have more free hours then hours spent mowing. There is no reason to justify spending money to increase production capacity when you are far from being maxed out now.
I favor a rider because one hand operation.
And the 500 (maybe the 300 also) looks to have rear wheels large enough to back up over curbs to mow islands in parking lots. People say ZTR's can do this with no problems.
ZTR's and riders come with decks up to 60"
Thing is a ZTR has this one advantage. The have much faster speed/mph.
12 mph may not sound fast but it's alot faster then 6-8 mph.
I have a JD 180 LT 42" rider. It was bought for personal home in 2003. So as with most people starting out they use what they have till they can afford to move up. It cuts great, but slow when compared to a ZTR.
Though I have more hours then I have work to fill them. So getting a new mower is low priority.
For me replacing my 4x8 trailer is more important. What good is it for me to get a bigger mower when my 42" is the largest mower I can get on now.