My conclusion that I had Acamd working with GBPVR (http://forums.gbpvr.com/showthread.php?t=33120) was wrong. It worked, but for some reason it stopped working (no picture) and it's going on and off now, so it's not stable or reliable yet.
On http://forums.gbpvr.com/showthread.php?t=33309 you are discussing a new MDAPI and I've seen the subject on dvbn.happysat.org.
What I'd like to point out that Acamd is working perfectly with ProgDVB, so I wonder what the difference is with GBPVR? Is ProgDVB using a different MDAPI, or something completely different?