Assuming VFR flight (I am not up to date on IFR).
You will not need a transponder at all next year to fly from your strip.
The Filser is, as has been said, lighter, cheaper and has a built in encoder.
I have not come across the air/ground-switching requirement at all. Is this IFR or all fits? I do not see how this could be done in some F/G aircraft. It was not mentioned at any of the CAA meetings I attended.
Rod1