I've been working with the HD60 Pro for a few months now as a preview user. It's a solid card.
At present there's only 32-bit support, but a 64-bit driver should be coming soon.
Direct 'Video Capture Device' cap in OBS has a bit more delay than using their software and capping that.
Best-possible, use AmaRec 2.20c (not 2.31) and monitor or DWM capture that in fullscreen.
Via Amarec, it's on even footing with the SC512 and even a Datapath Vision E2 as far as latency goes; I'm planning to put together a new capture card shootout video soon demonstrating the differences.
OBS Capture- ~150-200ms (Not sure what OBS does differently, but it causes a LARGE spread in capture rates, and a major capture delay increase)
GameCapture HD - ~50-150ms
Amarec - ~20-100ms
That said, I still consider the SC512 to be the best cap card on the market, for 'serious' livestreamers. The ability to grab component/composite/s-video/VGA as well as HDMI pushes it over the top for functionality, especially with SabrePC selling a version without the passthrough daughtercard for $200 as the Yuan SC512 (though you'll have to buy a DVI->HDMI adapter for $7, and deal with using splitters before the card instead of having a passthrough port; otherwise it's literally the same card, down to the silkscreening and headers).
The HD60 Pro has other things going for it though, that serve to balance out the functionality.
Availability is a big one. No mucking about waiting for new stock to come in. You want one, plunk down 200 bones and it's on its way.
English support is huge... with the SC512 if something goes wrong, you've only got the community to fall back on unless you speak Japanese or Mandarin. Elgato is right there and on top of things, and super-responsive to the community. They constantly are updating their software and stomp bugs fast.
Ease of use is a lot higher. Their Game Capture HD lets you just grab and go, with editing and recording right there.
I haven't had a chance to use the local-recording on-card hardware encoders, but that's going to be a massive help for anyone looking to preserve full-quality game video for later editing, like with highlight reels.