I didn't go a half size down. They were a little roomy. Put a second pair of socks on, and now they fit like a glove. So well that I ordered my replacement warranty pair at the same size.
They definitely run slightly big.
[Yonex RQiS 1 Tour XL 95 - Cyber Flash 16 (M) and Tonic 16 (X) @ 60]
[Yonex RD Ti 80 Lite - NRG2 16 @ 55/53]