There are plenty of fun FTA signals on
C band - mostly DVB but also some analog and Digicipher II. Like you, I had a nice motorized 90cm dish/Ku-only DVB FTA setup and decided to 'add' C band to that.
At first I put up a separate 10' mesh dish. That worked but what was cumbersome in practice was moving each dish separately. I chose to use a 4DTV receiver to move the big dish. If you use a V-box that problem could go away (by connecting the V-box between a
DiSEqC switch and the big dish). The linear
actuators common on big dishes themselves are not DiSEqC compatible and require a different kind of mover, such as a V-Box or a second receiver designed to handle a 24/36V actuator motor and position pulses. I expect that to change, as for instance
Sadoun already sells a new H-H motor that can move what - a 1.8m dish?
Eventually I moved residences, and having a chance to start over, decided to do C and Ku band on that same 10' dish, at the same time choosing a C/Ku band LNBF and doing away with the Corotor type servo feed.
Now finished, I'm much happier with that setup than the old two-dish one. Ku does require careful and time-consuming
aiming on a 10' dish (very narrow 3 dB beamwidth - about 0.4 degrees!), and minimal play in the actuator/dish hardware. The actuator also has to have sufficient pulse resolution to allow moving the dish in very small increments.