It looks like you are looking at the L series - That is a good thing...
I have less land than you, and a small orchard. I started with the B series with a loader. After two years I had only 96 hours on the tractor, and that was all from mowing. The bucket was to small to do a lot with and can only lift around 500lbs. I found I took off the loader and never really made use of the B for much more than mowing... Tried tilling with it, low ground clearance required the removal of the MMM to do anything int he garden, and the 26 HP was fantastic as a mower, but int he garden, all that HP was wasted as the little B would just spin the tires. The brake pedal was above the hydro control, so there was no way to do precise work with the loader... etc..
I have since sold the B and bought a 35HP tractor. I made my first payment on it last week, and have already put 26 hours on it. With the weight it puts the HP to the ground, unlike the little B spinning the tires and diggin itself a hole. I was able to till the garden grade the drive way, plant more trees, and having a proper sized bucket that can lift 2000lbs, as well as the quick attachment system sure makes planting and watering the new trees a joy. I went with a finish cut mower to do the mowing(about 4 acres), 6 feet at a pass makes the yard work go fast. In fact you may want to reconsider mowing the large portion of your yard with a finish cut mower, keep the ZT for the close up work.
I am not bashing orange, or the B - it was a great tool, it started every time, and never gave me any issues at all. It was the first tractor I bought, and I made a mistake by going to small for my needs, good thing about the orange, I did not lose money on the tractor swap.
My suggestion is buy more tractor than you need, having a tractor that is a little bit larger is a much easier problem to live with than having a tractor that is just to dang small to get the job done.