When the comment about the powdered metal gears was read I did go to the HydroGear website and looked up the literatuare on both the 2800 and 3100, the 3100 was listed as having steel cut gears and the 2800 was not, so I sent out an email to the Company and asked-I'll post what I learn as soon as I learn it.
I have not owned a zt with pumps/motors so I will cede to your experience, I had understood that the intergral units were 'noisy' compared to the individual components but this is not what you observed with your Grasshopper and I find this interesting. Of course the lack of hoses and fittings is a big plus in my mind.
As I mentioned previously had JD offered a deck smaller than 48" I would have one in my shed as I type, I liked what I saw when I looked at them; and the price was certainly not any more than what I paid for the Exmark, $3800 or so. As you can perhaps tell I am not a Briggs person and I was very concerned when I saw that Deere had left Kawasaki for BS BUT I also was impressed when I saw the way the Briggs was set up for Deere and even more put at ease when I realized that the 'Professional' series engine is , at least in the literature, put in a different model class the the 'ELS' series which I have (and dislike) in the Exmark.
My dislike for BS is based on experience rather than opinion, the last two engines I have had by Briggs did not give satisfactory performance or service life-the Vanguard in the Simplicity did not give even 350 hours (twice yearly synthetic oil changes with twice yearly air filter changes) and an Intek on our DR vacuum is smoking badly at not even 70 hours-same maintainence schedule.
Contrast this to the four GX Honda's (one of which is about 30 years old and still start on the first pull after winter storage) and a couple of Robin's which have been 1000% reliable and the difference between Briggs and others is apparent.
BUT again, the 'Professional' Briggs -seems- to be different and even I would have taken another (but final) chance... and, there are many thousands of Briggs owners who claim to have had no issues.
I think you made a good choice and I will be interested in reading your comments on performance in the future-do you know if Deere offers their satisfaction warranty for the ZT you bought?