He can have a try of my Maxxum Syncro,see which one he prefers then!As @Pheasant Surprise says you have made a cock up. Using a fendt then moving to a different make is always going to be a bit of a disappointment.
The fact is fendt vario is a dream to use. I have just bought a secondhand tractor with gears and powershift. How primitive it feels!
I would offer one of your men the option of a fork and wheelbarrow or the kubota. He will soon get used to it
I do take the point of the Kubota's operation being completely different to all other Vario equipped tractors and can see the problem on a mixed fleet.