I bought an XR4145 this past July and have about 20 hours on it so far. Mostly moving stuff around with the loader, box blading some trails, a little backhoe work, skidding logs, etc. I have had no issues at all so far. It is a very smooth ride, even for a 3-cylinder. I have not hit regen yet, it is supposed to happen every 50 hours. I have an open platform, gear shift model. I didn't want to the cab for the woods. Too many tree branches. I have a commercial front mower with a hydro trans and that works well for that but I have always used a gear trans on tractors. Just preference. The shuttle works well for FEL work, although shifting between ranges is a little clunky. I think it may smooth out after it has broken in further.
Besides the shifting, the diff-lock pedal is placed very close to the shift lever boot and I could see that boot getting ripped after a while. Just something to watch. The only other thing I've changed is to re-route a couple electrical connections behind the operator seat. They were wrapped around the support and zip-tied in place but they looked like they might wear after a while. Took about ten minutes to re-route and tape up. The toolbox is handy, although a little small. I will probably replace it with something bigger in the near future. There is no cup holder. Shouldn't be a huge deal but I always have some water or something with me while I'm in the woods and there isn't a convenient place to keep it.
Overall, it is a powerhouse. I have loaded rears (R1's) and I have been pulling some pretty heavy logs up the sides of my ravines with very little wheel slip. Just load the FEL bucket with some wood and it is just about unstoppable. I bought the 6' LS rotary cutter and it doesn't slow the engine at all, even in heavy grass. Time will tell if there are issues but so far, nothing bad. The 5 year warranty on the emissions stuff is helpful. I figure if something is really going to go wrong, it should happen in 5 years.