My wife and I went through a nearly identical experience about 4 months ago at Crank-2. We have about 1000 miles on our DaVinci now so I can give you FWIW my then and now take.
THEN
1. All the tandems felt a bit twitchy since we had a grand total of 20 prior miles on a tandem. When we took Bryon's standard 5 mile test ride I could feel the Co-motion turning in a bit faster on those mini-traffic circles.
2. ICS appealed to the contrarian, senior citizen geek in me. We have a 6 year-old grandson who we would like to put on the back some day and I thought ICS very appealing for the non-experienced stoker. This also applies to my twin adult sons - good bicyclists, but I don't trust 'em if you know what I mean.
3. Gearing was intriguing. We had just gotten back into cycling after a 20+ year hiatus and who would have thought we'd use all of those gears though?
4. My wife liked the color.
5. Even with the ICS we almost fell over on our first attempt to start on a slight grade.
6. We discounted what I thought might be very small weight penalty. I was a 190 lb. marathon runner so I'm of the "try harder" mindset.
7. Didn't have a real opinion on Campy versus Shimano although both our 1/2 bikes are Shimano

NOW
1. We love the bike. Our singles feel twitchy (and very rough riding) compared to the tandem. It can be a bit harder to relax in a crosswind or when there is a very small shoulder, but in a year or so I'm going to have to get an new single because of the plush ride of the tandem.
2. We like the ICS very much and I wouldn't think you would learn anything by riding a DaVinci with the ICS locked out, but the ICS can make the captain lazy and on any sort of a grade you've got to get your butt on the saddle and jump on it (and be in a low gear). My wife can't start the 40+ lbs of bike, my 200 lbs, etc. by herself (I won't tell you how this came to be revealed to me). If we were racing we would go with a convention drive train for a slight increase in efficiency and a slight decrease in weight.
3. We use the entire gear range. We're running a 12-27 cassette and this helps keep us in our cadence overlap. Since we're in our 60's this combo is good up to about a 10% grade at least until we get stronger. We can grunt up something steeper for a short while. You won't believe how fast you accelerate downhill thus the need for the 60(30) chainring
4. My wife still likes the color
5. See #2 above - We need to practice more on slow speed, small radius turns and on uphill starts. If the road is wide enough I've had to head downhill and make a u-turn.
7. Shifting - I really prefer the Campy shifter now that I'm used to it. An indexed FD would be perfect, but we use all four chainrings and as advertised I can use a good number of the cogs from each chainring. My moto is "When in doubt, go low" meaning don't be reluctant to go to that itty-bitty 12 tooth chainring. The Campy shifters allow me to move 2-3 cogs in the rear as I drop from the 24t to the 12t chainring. You'll appreciate the fast RD shifts: doing rollers we need to downshift quickly 3-4 times on the way up.

SUMMARY - They are all very good tandems. We like our DaVinci, but we would be liking any of the tandems you're considering. Good luck and hope to see you on the road soon.