I agree with the above. The advantage of a Circe Helios is that it is really stable and easy to ride, with or without a stoker.
Circe themselves have a rental side
Blue Yonder if you wanted a longer try. My stepson (TGL) has asbergers and was very nervous on roads, but coped on the back of the big tandem (700c), for touring. I used to ride his bike so he could ride on the quiet roads.
If you are in our vicinity, you would be welcome try ours. Our Circe Helios has E-assist which is brilliant. Our larger tandems (700c and 26") are in storage at the moment, but are likely to be out in the fairly near future.
If you want to try a big variety, a day at JD Tandems in Gargrave is worth the effort.
Another advantage of the Circe Helios is that they are highly customise-able and if you can choose what suits you. This applies to a certain degree with their other model, the morpheus, which suits some people better for various reasons.