I cannot comment on the Voigtlaender Prominent but owned and used an Exakta66 Mod II. After using a PentaconSix (that was my first MF camera) for quite a long time and owning some Carl Zeiss Jena lenses like the 50mm Fektogon, a 120 and a 180mm f2.8 it was a logical step to get the Exakta. Unfortunately it showed the same flaw like the PentaconSix, i.e. non equally gaps between the pictures on film. In some extreme situations the pictures were overlapping. Compared to the PentaconSix the ground glass has been improved (some kind of bright screen from Rollei) and the prism finder as well and the overall precision feel of the camera body was in another league. The Schneider lenses were on par with their Zeiss counter parts being used on a Hasselblad, if not better. Film flatness has been much better than on the PentaconSix. The lens mount allows to use PentaconSix lenses, Kiev66 lenses and dedicated (Exakta) Schneider lenses as well. The shutter release on the camera's front was a big plus in order to avoid camera shaking. Flash sync has been awfully slow (1/25s if I recall properly).
Hope this helps a bit.
Regrads, Udo