Thanks, We have 1 extender but its mostly used at weekends so the problem wasn't noticed until today.
1. The SD audio problems is fixed, I changed the recording graph which seems to fix it. I think the problem was that I was using the NVIDIA HDTV demux and I found that it has problems when you change channels unless you stop and restart the directshow graph. This gave me a bunch of headaches trying to sync channel channels and recording. I ended up using the NVIDIA TS p a r s e r and Microsoft MPEG demux which handles channel change without problems.
2. I believe so but haven't looked carefully. I have tried the NVIDIA audio decoder and AC3 both worked with an external SPDIF system. I have seen the audio bandwidth at 384Kbps so I would hope its 5.1!
3. Definitely on my system. HD is very noticably better (it looks the same as HD from the STB directly to the TV via component, whereas through the MCE it looks out of focus in comparsion), SD is better but not as obvious, with my NVIDIA tuners I have a problem with washed out color with certain very bright video, this does't happen with firewire. For SD the file sizes are about the same, for HD much larger about 3-4 times the size.
4. That would be tricky, I haven't really thought about it as I currently use the MCE file to obtain all the attributes MCE uses. I would have to find another way e.g. the guide to get the same info. I would also need to solve the seek problem. Also I dont have a problem with encrypted channels but other people do, I was planning on always letting MCE record but looking at the firewire file after recording has stopped and if it looks good deleting the MCE file. So if the channel was encrypted you are left with the MCE file rather than nothing. I leave both there for now, once I am a bit happier with the reliablity I will move the MCE files to another directory, so they dont show up in MCE but they are available if there was a problem and then much later, delete them.