The Kubota appears to fall between the x500 and x700 Deere's. Haven't tried out the Kubota steering but it would be good to try driving it up a steep slope in a sharp turn to see how well it works out.
Just from the specs the Kubota is lighter and I consider that a good thing for mowing. The new Kubota adjustable seat looks very good too.
The Deere is about 30% faster, 400 lbs heavier, electro hydraulic pto clutch, more hp and hdap 26 12 12 tires.
Gets down to personal preference imo, I bought the Deere but think the Kubota unit looks very good too.