I fly with two other S7 Kitfoxes that have the microair radio. Only one of these has the corresponding microair transponder.
Both pilots liked the small size and neither has had any electrical problems with them.
I have been the passenger in one of these Kitfoxes where the pilot expressed some disatisfaction with the physical size of the control knob. Seems it is smaller and thus more difficult for him to toggle between channels or switch channels.
Both pilots have said they are happy with the range and clarity of the units.