Hi Jen and DD,
Just picked up on this thread now. For what it's worth, I rode this bike about 4 weeks before you purchased it Jen as I too was thinking of buying it. I only took it for a quick squirt around Mt Wellington streets. Definitely noticed the miss lower down, but it was no where near as bad as in the video clip. Also, it went like a shower of shit above 5k, completely opposite to what you describe. It felt much faster than the Ballabio I ended up purchasing that week. Granted, the CS was the first Guzzi I've ever ridden, and the Ballabio only the second but both ridden on the same day. Thought I would share for what its worth, as it could indicate a degenerating cause or at least that the bike was running somewhat okay recently.
Keen to see how you progress with getting the bike sorted, I'm sure you'll get there eventually. Good luck!