See if your dealer would let you rent or try out a stander first.
If the slopes are too much for a z-turn, a stander may also have issues.

 

This sounds like the right job for a stand on unit. I had a similar situation to yours re: slopes and shopped around for the stand on that had the best hill stability. Some are better than others. You'll want something with a low center of gravity and larger tires. A few years ago that was an Exmark Starris. They no longer make these, so I don't know which brand is best for hills these days.

Note that, even on the most well suited machine, mowing steep inclines can be a challenge and feel dangerous at times. For example, I have learned (by losing control and sliding down hills a few times) that there are certain areas of my yard that I have to navigate in a specific way. Additionally, I do everything I can to avoid mowing my lawn in the mornings or other times when the grass is damp.

Another consideration is that stand on units are more maneuverable than the lawn tractors (and even sit on zero turns) and will cut down on mowing time considerably. Stand on unit are also supposedly easier on the back. I love mine and can mow my lawn in half the time my neighbor can (same size lawn, same size cutting deck) on his JD x590.

 

Noting everything you said.
I'd add that I've compared the John Deere stand-on and the cheaper Toro Grandstand....I'm looking at a 36 inch deck by the way.
One BIG thing I noticed is that on the Deere you are practically standing on the rear axle....a good think feel for putting more weight into traction/versus the Grandstand where the platform sticks out behind the stander. Maybe not a lot of difference? I've not calculated a moment arm of torque force in a long time.

I do like Toro though but the family/father in law has JD lawn tractor and gator. Might give me family bonus points to add the Deere

Non-mowable areas. We've only ben in this house for 4.5 months and there are quite a few areas in the yard I will not take the Kaw Mule near....it has been lifted and larger than stock tires (snow plowing) but still I've got a good feeling for where not to even venture on a stander. The wife is in on this and agrees/contributes ideas to what ground covers can be planted in those areas.

Now everyone is an expert on Youtube right haha! But the vids I've seen show stand-on mowers to be much better on slopes than tractors or zero turns, plus the easy bailout position which I plan never to get into (famous last words). So I think, well I know that is the direction I'm leaning (pun intended since you can lean into the standers for even more stability.

 

Do you have gates to go through?
If I had 1.5 acres I'd want a larger deck than 36", unless you have tight areas to get around.

 

Do you have gates to go through?
If I had 1.5 acres I'd want a larger deck than 36", unless you have tight areas to get around.

+1. Not to mention a 48 or 52 model is going to be more stable on hills.

 

A stander may be easier on your back but harder on your knees. I purchased a few Z997s and Z994s for a facility I manage. I spec'd them how I would want to use them if I had to do the job. The grounds crew couldn't be happier. Suspension seats and Tweels take out all of the harshness. Not sure if you can get Tweels for the tractor but the suspension seat is a worthwhile upgrade. If slopes are of real concern, seeing your average but not knowing peak, you could look into a slope mower like a Ventrac or Steiner slope mower but they are considerably more expensive new and may be a little overkill for only 1.5 acres.

 

I spec'd them how I would want to use them if I had to do the job.

This is the way...

The 997 especially is not a "disposable" piece of equipment or something one buys to knock out their 1 acre lawn 1x a week. Built like tanks, to last, or at least they were when they came out nearly 20 years ago. Built to the same standards as the front-mounts - tough. Might as well spec them out to run all day and not wear out the operator!

 

Came here to mention the possibility of the Ventrac/Steiner tractor. I am looking at the possibility of replacing my zero turn, polaris, and tractor/brush hog with one of the ventrac tractors as an all-in-one solution that would let me cut down on storage. Half of my 4.5car garage is presently storing lawn and garden equipment for our property.

 

Very spendy solution for a 2acre property. Unless the OP is mechanically inclined and doesn't mind one with a bunch of time on it.