We had a lot of trouble with a similar type of heating at a unit we rented for a while. We had them suspended from the ceiling. Ours were gas fired but worked in a similar manner.
It heats up any work surfaces under the heaters and made our optical bench practically unusable - we were setting up landing light systems for airports - the bench got hot but the units were cold, so we had to wait for each unit to heat up on the bench. The staff were complaining about cold draughts round their feet and overheated heads.
Amixture of both may be better, the radiant heaters warm the benches and a propane blower to warm the air.