I would be tempted to give it a go.
Not speaking from experience but the folks I know who have done this mod on the current SLK have reported that, baring the sun light sensor, (lack of), conection/s + the charcoal filter not being there, everything works as it should and looks a whole lot better than the standard A/C control panel.
I believe the panel for the SLK can be picked up for about £125 on e-bay as opposed to it being a £400+ option on new.
Portzy.