Maybe small to you since you're on half inch ropes but 8mm is a pretty common hitch cord for 7/16" ropes, particulary with knots like the VT.
The only time I've used anything larger was when I was on a Blakes with a single eye split-tail... I take that back, I used the fat Tenex (yellow, single end per carrier) eye-eye from Sherrill with a Distel for a while.
For my size, rope, hitch and all the other factors, HRC has been the bee's knees as long as it's spliced to be 8mm (you can splice it to be thicker). Very responsive but grips easily. It gets too stiff when spliced thick and has to be manually set sometimes.
I just started using 8mm Ocean Poly after TCIA and I think I like it better. It sets every time without worry when using an XT (VT with a twisted braid). It doesn't flatten out or glaze easily... relatively expensive but considering how critical the hitch is, it's cheap.