That might be. But presently all the high end medium format backs use CCD as reported by Michael in his recent essay on the subject.
Of course, current gen is CCD. The discussion topic here is the next gen and I guess we've drifted into technology details because of the rather specialised readership
In the mean time, speaking of current generation (since Photokina), here is a document which might explain what the Phase+ backs do. It would seem that they've implemented hardware charge binning, with extra registers at the top and bottom that bin R with R, G with G, B with B. The same structure allows live preview extraction.
The 44x33 mm chip presented resembles the P30+ size rather closely
- Selectable resolution
- Four times sensitivity
- Three times faster readout
+ 6dB SNR gain in photon noise regime.
+ 12dB SNR gain in read noise regime.
Of course, if this is what's done then running at hi-iso would mean dividing the file rez by 4. Useful nevertheless, but not quite what the Phase marketing guys were saying at Photokina (they were saying full rez at hi-iso).