It can be done and it can work quite well. My glider has no TE probe
and is equipped with an old Peschges VP4E NAV vario which is set up
for electronic compensation. In order for electronic TE to work
properly though the pitot and static systems installation must have
little to no inherent error. Not all glider designs meet this
criteria. If you go back and look at the Johnson flight tests in
Soaring magazine you'll find that quite a few gliders have large
errors in the static system which can put the airspeed indication
several knots out (dig up the article on the Standard Cirrus for a
good example of this).