Some are jerkier when lowering with a load than others, just like human beings. Our L3400 isn't a problem, but I am not doing 3 point tasks where smoothness is critical. Ours is fine for simple scraper blade type work. I like the beefiness of the L3400's rear end, and the overall design and build- seems, to me, to be a well balanced tractor in terms of weight/power. Our previous tractor, a Kubota L3130, had about the same power but much more weight/traction, but at the cost of lawn damage and speed.
All that said, I know nothing about the Deere. Hopefully, you could test both machines before buying? Do you have local dealer support, should you need it? We have never needed dealer support in 15 years of Kubota ownership- I buy filters and such wherever cheapest, pretty much.