Those hours would not bother me in the least. Also once you get up into the utility size class of tractors ten years old is in most cases relatively new. I farm with two tractors built in the 60's, one built in the 70's a 2002, and a 2012. The three oldest are all well north of 10k hours but have been maintained well and run like a top.
With the 5410, they are very good tractors and were on my short list when I bought my 2002 TN75D about a month ago. Parts are very much available. Deere is actually really good about this. I can still get parts for my 4020's though deer and both of them are sixtys models. Also no problems getting parts for my 74 ford 3000 through the new Holland dealer either.
With Kubota being one of the major brands now I don't see any real issues with getting parts for that tractor either and would expect it to last many thousands of hours more before needing to be overhauled.
As for the low hours on a ten year old tractor, as long as it has the appearance of only having that many hours it would not surprise me in the least bit. Often these tractors come off small horse farms that require a tractor in that size range for moving hay, but they don't do allot of other stuff with it. They might clip a pasture one or two times a year, or plow a bit of snow and maybe some paddock cleaning but it don't take allot of hours to do that on a small operation. If your not making hay or working lots of ground it don't take allot of hours on the tractor to get everything done.
That being said. If you plan on making your own hay in the future all of the listed tractors are capable, but would be on the small side for running a round baler. They will do it with properly sized equipment, but if bailing is in the future and you only want to have one tractor you may wish to go a bit larger, or do what many others have done and when the time comes invest in a second larger tractor. My baler requires 60 horse at the pto and although all of my tractors with the exception of the 3000 are capable of running it I still pull it with the old 69 4020 that has an aftermarket turbo and the fuel feed turned up a touch. It makes the baler run much better with an abundance of hp verses barley enough and I can bale faster and make better bales as a result. I also do most of my plowing with that tractor as well and pulling 4 18's in heavy clay will make her snort pretty good quite often.
