There is a huge difference between the traditional Kawasaki Mule (600, 610, 4010, etc.) and the PRO-FXT line.
The PRO isn't going to compete with a RZR or Teryx in terms of speed, it isn't designed to. I'd say it's a decent mix between the traditional utility Mule and a more sporty SxS. Mine tops out at 43mph, and I'll tell you that outside of my neighborhood where we cruise on the roads, there is 1 spot on my entire deer lease that we can even approach max speed and that is on the improved main all weather road. Any other place outside of that and speed isn't a concern at all.
I've been pretty happy with my PRO-FXT since I bought it in 2018. Very few problems, very reliable and overall a great SxS for both utility purposes but also for my girls to cruise around in. Both have learned how to drive on that mule.
What puts it above the others IMO is that it can go from a single seat configuration with a large bed for hauling feed, etc. to a 2 seat configuration in about a minute. Any other model and you have to choose between a short wheelbase single seat that performs best offroad or a long AF wheelbase 2 seater.
It isn't without faults or improvements needed, but for me it was the best option at the time because of the versatility and reliability. There are 5 of them on my lease and we run them hard, especially during the season when it's typically muddy as hell. 2 polaris rides are decent (old farts put them around), 1 polaris is a heap of sht, another guy has a Viking (I think that is what it is) and it has some great features but also some drawbacks and another guy has a 4010 Mule that isn't sexy but he never has a problem getting to his area and back.
https://instagr.am/p/C4N4Ok9udYP