Italy
I tried to install the Hauppauge USB DVB-T stick and tested it. I disabled all tuner on the HVR-4000 except the DVB-S tuner and made a channel search for the USB tuner. Everything works fine as I expected since the DVB-S tuner is on another independent card. What I expected, and I read and I've been told was true, is that the DVB-S and the DVB-T tuners on the HVR-4000 are independent and work separately, and I still think is true.
I installed the trial of Powercinema 5 from the Cyberlink site and made all the necessary operations using only the HVR-4000. Switching from one DVB-T channel to a DVB-S channel works like a charm, it just takes a little time, I think the program needs to unlock one tuner and then lock the other one. The only thing I noticed wasn't working is the Twin TV mode, but I didn't get through it since it wasn't the purpose of my test, although this could be a useful functionality.
I installed the trial of Powercinema 5 from the Cyberlink site and made all the necessary operations using only the HVR-4000. Switching from one DVB-T channel to a DVB-S channel works like a charm, it just takes a little time, I think the program needs to unlock one tuner and then lock the other one. The only thing I noticed wasn't working is the Twin TV mode, but I didn't get through it since it wasn't the purpose of my test, although this could be a useful functionality.