I've been running the HH2 for a couple months now and really coming to enjoy it. Normal setup has been Vortex and ocean poly 10 mm, 5 wrap hitch. That's been really great, tends very well, but I was running my hitch a tad loose so I had to set it once in a while.
Today tried running velocity with 8 mm bee line. I like it but have to run the hitch nice and tight or it's too jerky descending. Gonna try a few hitches before settling but I am pretty happy so far after hearing the HH2 doesn't like 11 mm rope.
Also, just got around to adding a fixe pulley as a fair lead, same setup that most of you run. I've only got a little time on that particular setup so far, but my impression is that the system tends slack better without the pulley. Without the pulley, you tend slack upwards and the rope engages and pulls the carabiner upwards. I think this extra contact keeps the carabiner from side loading. I am pretty sure that the smaller diameter rope does allow for a little more lateral movement of the carabiner though.
I really prefer having the ability to take several arm lengths of rope between tending when coming in from a limb walk. I will probably do a comparison this weekend to see if the system performs better with/without a fair lead when using a 3to1 on limbwalks.