I've used the Sinar one in a studio on a 4x5 camera, works extremely well for transparency work, which is really why they were made. That was in the mid to late 80's.
I have the Gossen Profi-six with the 1º, 5º and 10º settings as you do, plus I have the fibre optic thingy for ground glass readings.
The fibre optic readings need calibration, then you are off. However to be honest I take a light reading, usually reflected of the subject, measure the bellows extension (if any) make adjustments then shoot. Using B&W negative film I have never really had a problem.
Mick.