Hydrostatic is a proven system... it will likely survive the life of the tractor without needing expensive repairs. That Mahindra dealer is probably saying that because he wants that unit sold cause that's what he has present (my guess) ... I would still highly recommend hydrostatic. The negative with hydro is that it robs some of your PTO horsepower (because the engine is also spinning the main hydraulic pump) but really, for the uses you describe, that won't be a concern.
If the price was identical (between the Kioti and McCormick) I'd go with whichever dealer you prefer. But, are you referring to the Kioti nx4510? You wrote 5410 ... the nx series is a tier4, and will have added emissions equipment.
That McCormick (x1050h) is a DK50 (tier 3 model) so it won't have the tier 4 emissions. Also, I believe the "h" in the model refers to hydrostatic, which may explain why it's a little more expensive. My guess...
Also, I wouldn't worry about the McCormick and long term support, even if McCormick stops buying Daedong tractors to rebadge. They'll still be required to honor warranty claims in the warranty period, and then you'll be able to get long term support from a Kioti dealer if need be, same as Kioti.