I cant say nothing about the Koiti but have been running a JD 4120 P/R with 400X loader for more than 5 years now and it has been trouble-free. I have not needed any parts other than oil filters. It handles a 6 foot bush-hog with ease in any field conditions. There has never been a time I felt a need for more power and I understand the newer ones are up a bit here so you should have way more than enough, especially without the efficiency losses of a hydrostatic transmission. I also use an 8 foot pull-type disc behind the tractor on occassion and it does not even seem to realize that the disc is behind it (unless I disengage the 4wd, when I have to boost the throttle a good bit to maintain ground speed). It will pull that disc, fully angled and engaged, in 4wd, at a low idle. The ride is quite comfortable. The loader works great, just be sure you get the heavy-duty bucket. On rare occasions, I do use a set of forks up front and I can see where the leveling feature of the CX loader would be nice. Thankfully, I have enough tractors that I dont need to change implements too often but if I had it to do over, I would get the telescoping lower links to make that process a little faster. I am sure the Koiti is a fine machine also, but it only costs a little more green to go first class. For me at least, it has been well worth it. Back when I bought, a comparable Kubota (GL 4330) was about $1000 more and an NH T?40 was the same price when I added quick-attach bucket (standard on the JD), but significantly underspec'd in hp, lift capacity, etc.. We didnt have any Koiti dealers around so I never looked there, while I got a JD dealer just down the road. He was high priced compared to the dealer I bought from 50 mi away, but very convenient for oil filters. He only caries parts up the the 4000 series (top of the CUT line), or I probably would have sprung for a larger, utility model.