Have ridden/owned steel, alu, ti and c/f singles and tandems.
All are good and have their merits; however, our butts are on a carbon fiber tandem.
Just our experience/opinion/choice.
There is no mention of how much cheaper their CentrAl would be, but said it could save billions (with a 'B'!) in the aerospace industry. Weight is 20% less than carbon fiber.
Most of their info is in Dutch and/or English.