I also have a X595, and put a 3pt on it when I bought it several years ago. I use it very infrequently. It was expensive. And I couldn't justify the rear pto to go along with the 3ph to enable attachments like a cultivator. So any app's to use the 3ph is limited to smallish blades, smallish box scrapers, smallish landscape rakes -- all of which are embarrassingly expensive if you buy from the JD line. And they're rather light, which compromises their usefulness.
Thank god I also have a JD4700 to take on the serious work.
The 595 is great for mowing on slopes though, which is my primary need.
jim