Hitachi made the deere machines in the start, deere put their own engine's in them, can't verify it but the rest was supposed to be the same, deere is supposed to have marketing rights now for the hitachi machines in the USA I've been told. I don't have experience with the deere machines myself other than the older one's they put deere engines in and I own several other machines with that same engine in them, they didn't want to start when it was under 50 degree's out, were not that fuel efficient and had issues with every size they had.
IMO, the Isuzu is the way to go, have had a few of them and never had an issue with them, start in extreme cold weather, probably start when it too cold out in fact, maybe they shouldn't start that good when it's 30 below zero, but they do start and run fine, never need either to get them going..............ever. and are a bullet proof engine as far as I'm concerned.
Now that said, its up to your dealer or network of dealers, for support, meaning your dealing with Deere and they have the tendency to change their minds on things like corporate relationships, then independent dealers have their own idea's on what to back or not back for parts and support, and those dealers change their minds as well, what they sell new today and promise they'll fix for 20 years with no issues, tomorrow they'll cut a deal with another vender and rather sell that brand and back it instead.
I've had parts and dealer issues in my area, along with deere's idea's at corporate level and when Hitachi went away and deere got them, there was a tremendous turmoil in my area on what they were or were not going to back and who was responsible, basically I had an excellent Hitachi dealership near me, and the next day, they were out and deere got hitachi and knew nothing about anything, no parts numbers, no service manuals, no experienced mechanics, nothing and the story changed daily on parts prices and availability.
Any machine is only as good as those that support it and back it, now not to knock deere or anyone else, its corporate America with any brand today, take your pick on which one you want to deal with and what set of problems you want to deal with as well, but Hitachi machines are great machines, the network to back them used to be great as well......................