This decision is a no brainer for all us Kioti guys, that's for sure, but I can tell you're a little stuck on that Kubota. The Kubota L3830 is a fine tractor for sure, but I'm not sure you're getting a steal at $16K for a tractor that is 6 to 11 years old. If he will take $14K, it sounds a little better, but still getting to an age where tinker time comes into play. The L3830 doesn't come close to competing with a DK40 IMHO. It is 1000# lighter (where's all that steel?), the FEL lifts 1000# less, is 3 cylinder vs 4 cylinder etc... I'm a big fan of the LXX40 series that replaced the LXX30, mainly because of the new HST transmission and the added lift cap. of the FEL, but the LXX30 series has the same style HST as the DK series and a lot less lift.
Don't ever expect un-biased advise on TBN, and I'm not trying to give you any.