I agree with the general direction of spending less and then figuring out what does and doesn't work. But if you already have experience with a tandem and a bunch of miles together on a tandem, you should be able to figure what you need. Overall, fit and spec are going to be more important than Santana vs Co-Motion (or any other brand).
If you feel that your current tandem is too big, you can take the measurements from it and compare to the models you are considering. I'm sure people on this forum can help with understanding frame geometry as it relates to tandems.
Spec really also depends on what kind of terrain you ride, or want to ride. I'm going 2x on my new tandem, but getting really wide range gearing that a tandem needs in 2x is complicated. If you live somewhere more flat, I'd recommend 2x over 3x for a bunch of reasons.