As a kid we had Massey's with 6x2 and 8x2 transmissions. They were a real pain when loading manure and other such materials. Too fast in reverse hi and too slow in low and don't talk to me about shifting between forward and reverse.
My 2 MF563s have a mechanical shuttle 8x8 which is a God send in comparison.
I've moved everything reasonably possible and like it fine. No clutch issues in the years I've had the mechanical shuttle.
Really wouldn't mind the electro hydraulic shuttle but I no longer farm on any real scale and I'm good with what's here.
On smaller tractors, (up to say 30-40hp) I'd look into the hst tranny. Maybe I'm old school or just don't have enough experience with them but I wouldn't expect them to stand up to real grunt work in the long run on the bigger machines.