Well, I got the XD-15 installed on the V, and the V's old Ultegra bottom bracket moved to the Silvio. The XD-15 is very smooth and definitely spins easier than the Ultegra. I haven't taken it out for a 'real' ride yet, just a quick spin around the block to see how it felt. Felt good. Not sure if it feels $200 good, but whatever. I don't really have any regrets, I guess.
But here's the kicker - my Silvio still has the creak! I thought it was coming from the bottom bracket, but clearly I was wrong about that because I swapped that out. The cranks and pedals seem solid. I don't think it's coming from those. So I came home and put the bike on the trainer and started spinning the cranks by hand, while next to the bike. Hmm, sounds like it's coming from the headset from this angle. OK, so I took the top bolts and spacers off the headset - everything looks fine, put it back together, nice and tight. Still a little bit creaky, but not as much. I looked around and didn't see any cracks.
I keep using the word "creaky" to describe the sound - it's really something in between a creak and ticking sounds.
At this point, It doesn't seem like anything I need to be concerned about - just an annoyance. Anyone have any thoughts or ideas?