I have the 2706E (same engine and trans). I only have 7 hours on it, but so far I haven't had any trouble with the hill. I don't use High range except for road travel, as the mid range is fast enough that I tend to bounce a bit on my land. Flail mowed tall grass uphill in mid range without trouble. High range takes a bit to get to speed if you just step on the forward full pressure off the bat. Most people get confused by Hydrostatic and treat it like a throttle in a car. If you start to load down you need to ease up and let the engine catch up. Only hold it down far enough until the engine starts to work then keep it there. Ease into the motion and you'll be happier with it. Also run at PTO speed when you are going to do any work and the tractor will be happier.
Shibaura makes the engines for the 2700E series and the new 1700M series. NH used Shibaura in their skidsteers for quite a while (not sure if they still do). I've had very good luck with my Shibaura powered NH skidsteers. I also like the lack of DPF, DEF, and regen. That is the main reason I went with the 2706E over the 1758. Price and availability also had something to do with it, but the emissions was the biggest factor. I wanted hydro without a cab so the 1760M was out of the picture.