With a bit more time to play today I was able to ascertain that my previous SmartSDR connection issues seem to be down to some vagaries of the Parallels 8, Windows 8 stack that I'm attempting to use to host SmartSDR.
From the Flex Radio community forum it was already quite clear that people had managed to get SmartSDR working well on Parallels (or Fusion) with Windows 7. One of the bits of lore there was that you should use what Parallels call their "bridged networking", which associates a physical network device on the Mac directly with the virtual ethernet device that Windows will see simulated.
Despite some attempts yesterday, apparently I had never actually ended up with a bridged ethernet configuration that worked. I had previously used these Windows installations using the shared networking, which is fine for outgoing requests (e.g. browsing). It turns out that switching the networking to bridged can leave the stack a bit confused. In this state Windows claims that a network is connected but that it is "Unidentified" - but in fact even a browser doesn't work. Initially, I had left the wifi turned on for the Mac to use. It was certainly working for the Mac, but come what may I couldn't get the Windows networking to behave. However, when I tried turning the wifi right off, suddenly Windows indicated that its network was reconfiguring and indeed eventually displayed the network as "Network 6" instead of "Unidentified". At this point Windows networking was up and running. The browser browsed and, joy of joys, SmartSDR connected to the radio perfectly.
At that point I was naturally drawn right in to SmartSDR so left off further experimentation. It's quite possible that turning wifi back on for the Mac would have been fine at this point and left the Windows VM happily using the Thunderbolt device that it was bridged to, but that's an experiment to try in the future.
What I did try after a bit of tuning around and listening to various ongoing QSOs was to set up bridging over wifi exclusively. That all worked fine too.
With wifi turned on, I went for a bit of a wander around the house and noted that SmartSDR kept running happily. When I got back to the 6700 (which had a speaker attached) I did however notice that the panadapter was actually lagging behind the sound. I suspect that wandering around (I have multiple 802.11 base stations configured as repeaters to cover the house) had caused longer latencies that were reflected in this panadapter lag. I'm guessing that eventually Flex Radio might handle more networking conditions by being adaptive and resyncing as necessary. For now though, all I had to do was disconnect and reconnect when back near the radio (only one wifi base station hop) and everything was back in sync just fine.
Here's my first screenshot of a SmartSDR panadapter. I was curious about zooming right out to see the glorious huge bandwidth of the 6x00 'front-end':
Listening to a few QSOs on 20m I was struck by how great the audio sounded. At some point I need to compare with the 7800 some how. Tuning SSB just right on the panadapter was a little tricker than I expected, but I daresay that's mostly down to practice. I didn't buy the optional FlexControl tuning knob, so I was just dragging the receiver slice about to adjust it on the SSB signal. Perhaps I'll get more in the habit of zooming in for fine adjustments, or maybe there are fine tuning controls I haven't discovered just yet.
Anyway, the excitement pretty much starts here. I shall now properly set up the 6700 for operations and attempt a for SSB QSOs. After that I'll look into whether PSK operation is practical yet.