Actually, Jon, the HH comes with a 3/8" (10mm) Beeline with very specific instructions as to how the hitch is to be tied. But, I've only had the HH for a week. So, I haven't tried other combinations of hitch & rope - just RopeTek's recommendations.
On the RW, I like the 3/8" Beeline tied with a Michoacan.
As to comparing the two, it is very difficult. They both have very similar 'feel' when working. It all boils down to your personal style.
The HH is heavier but more compact. So far, it seems, the HH is more hitch sensitive until dial-in. To me, the HH is a bit more 'fiddly' to install & remove. And, you have to add (make) a very custom tending loop. Dave has made the coolest one, so far. I imagine Paul will address that issue.
The RW (with stiffy) is lighter but takes up more space on the rope and in the kit (because of stiffy). The RW is more hitch friendly (more options). The RW is slightly easier to install & remove. You also have to add a tending loop but it's easier to make.
Price is almost the same when you include any extra stuff required to be fully operational.
They are both wonder products - true advancements to the industry.
Your only choice is to buy three of each and decide which best suites your personal style.