Latest XTR, XT and SLX is indeed compatible with previous I-spec II.
The only "issue" when fitting I-spec II shifter to I-spec EV (latest) brake lever is 0.5mm too long screw from I-spec II. The solution is easy, washer between 0.5-1mm under the head of the screw and you are sorted :-) M8000/M9000 or M7000 shifters will fit just fine with new standart.
Sorry for a short film, just was happy to communicate you ca easly pair up old 11Speed Shimano shifters with new brakes from Shimano!
