I've just swapped from Penrite Hypoid 80W-90 to VMX-80, i found the Penrite to be HORRIBLE for the first 10>15 mins while the transmission was warming up. Second would clunk every single time. Felt like complete crap. It was alright for the first 1000km though ill have to admit but wasnt anything special.
As soon as i swapped to VMX-80 its improved dramatically, however ive only put perhaps 500km through it so far.
I might try syntrans next, i tend to swap trans oil at the same interval i do engine oils, considering a 4L bottle of VMX-80 is only $35 i cant see why not. Besides i only drive my GTR on street running 250kw. Hardly ever launch or put high load on the trans.