Somewhat off topic, but related with respect to being another reason besides the combo mode which make some DCII signals not compatable with 4DTV and some other DCII receivers. I have run across a couple DCII muxes that have {encrypted} MPEG4 video on them.
I would think that this would make them unplayable via most DCII receivers as well, and since the uplinkers can squeeze twice as many channels on there if they use MPEG4, I would expect this to be the trend, making current DCII receivers even more obsolete.
I had also noticed a bunch of transponders listed in Lyngsat as being 8PSK/DCII on the Canadian sats. I had mistakenly assumed that I couldn't receive these, however I found that these transponders are turbo mode, and the Genpix with TSREADER tunes them fine. Of course everything on the 8PSK muxes are encrypted, but if they ever go FTA they can be received. But again, this is another mode that allows the uplinkers to squeee 50% more content on the mux, and it isn't 4DTV compatable.
So basically there are trends like this which are money related reasons why some of the companies putting some of these thing on sat may be unwilling to bother with 4DTV viewership, since they can reduce their sat costs significantly by going to modes not compatable with 4DTVs. If not now, certainly in the future.