I love the SL-Cxxx keyboard. It's a great boon for mobile typing. But control-keys are not one of its strengths. With the Z I tend to avoid applications that make much use of control-key sequences.
As mentioned above, Fn-Shift-... can generally be used for Ctrl-... (if you can contort your fingers enough). Also, at least for some applications, Cancel-... works like Alt-...