It would be nice to try both. Unfortunately the small Co-motion is too big for me. I'll be checking out Santana tomorrow. I am very concerned about Santana's proprietary designs. If we get stuck in Italy needing a part that is not standard we'll be walking. I do not understand why Santana is doing this and you are the 4th person to warn me off their tandem. One sells tandems, including Santana, and he said he would never take one to Italy even though he very much likes the bike.
Hey we live in San Diego too (Encinitas).
Just reverse pilot and stoker and then you can find a bike that fits, unless you can't give up control?
We used to have a Santana, great tandems but I think the proprietary stuff is mostly marketing and the cons out weigh the pros, still worth a look though.
Never rode a CoMo so can't comment on those.