I have flown for years with with bifocals, and have no problems with them.
They are of the line type, and are especially made with the line high up the lens to accommodate IFR flying in plankers.
The strength of the low part is slightly more than would normally be prescribed, optimized for the distance of the panel rather than reading distance.
The top of the instrument panel corresponds to the line.
This set up also works well for me flying helis, although as a student I'm not doing "look down" work. I do miss out on seeing the graininess of ground references (i.e. blades of grass and lumps of asphalt), but manage to assess height nonetheless.
I would not hesitate to try bifocals set up properly for your flying if that's what the professional recommends.