We have a Santana Team Ti - build year is 1995. Bought as used (<5,000 miles by previous owner) and we have 2000 miles since January. According to Santana, it was a show bike with highly polished and burnished finish and came back to the factory for disc brake mount since that wasn't offered at the time.
We've been riding tandems since 1986 - rode a cheap steel Mel Pinto for a year to make sure we enjoyed it, and then upgraded to a custom fillet brazed 531/Ishiwata/Phil Wood steel by local builder Forrest Yelverton (Forrest later built Atlanta Olympic bikes for GT). Rode the Yelverton for 23+ years and approximately 45,000 miles. Test rode MANY other steel and aluminum tandems over the years but did not see a major improvement over our Yelverton. Have not ridden a carbon or the latest "super steel" tandems. Fyi, team stats are 280 lbs and 105 years.
Santana Ti has the same tires and saddles as our old steel, but came with many other upgrades that also impact ride (Santana carbon fork, Zipp carbon bars, Shimano Sweet-16s, etc.). No surprise that we immediately noticed a major improvement in ride quality - eliminates buzz on rough sections, and almost feels "suspended" on smooth asphalt. Ride is so comfortable that stoker no longer uses a suspension seat post. In terms of flex, can induce a bit more BB movement than old steel when climbing out of saddle and stoker remains seated, but no issues with timing chain or shifting. On descents, it carves like a knife.
Since we live on Colorado front range, have added Avid BB7, 220mm "floating" Formula disc, and EBC gold pads. Can now brake from 50+ to 20 mph on 16% grades with no rim heat, fade, or rotor warpage. Also added stainless Velo Orange fenders for upcoming "Ride the Rockies" next week. Current touring weight is about 36lbs without water bottles or extra gear; old steel was about 10lbs heavier.
Hope this helps!