A power reverser (EHHS) is a darn sight lot better than a normal syncro for tractor work.
It can make a long day in a tractor much more bearable, especially if doing a backup intensive job (loader work).
For the majority of time you put a tractor in a gear and can leave it there for a long time before you need to change again. Like when doing loader work filling a trailer from a pile or moving a short distance, you would only need to use the electro shift.
But if you were doing a job where you had to move a longer distance where you could go faster than you would have to change gear a bit (or just drive up to the pile faster and then clutch and roll into the pile and then power reverse and let the clutch out again).
For normal field operations you are not wanting to change gear at all so there is no speed changes.
I agree that HST is easy to use but very often you don't actually need to be able to change speed that often. Fergusons only had three speeds and reverse
Some EHSS transmissions also have the option to slide into neutral. This makes loader work easier again as you can speed into the pile, slide into neutral and get a bucketfull, come to a stop and then move the lever into reverse and go again all without clutching.
But, if you want a HST go with one and they are probably easier to use overall.