One of the main advantages of HDD/DVDRs over the old VCR technology is being able to pause and rewind Live TV.
The Panasonic DMR-EH68 does this ably and I can use the pause button found on the TV's remote. There's about a 2 second lag from pushing the button to something showing on the TV screen which can lead me to thinking "Did I push the button?" but by the time I've thought it, the scene I saw when I pressed the button shows on the screen in a frozen state.
From that point on the DMR-EH68 is in Pause Live TV mode and I can Rewind and Fast Forwad the action to skip ads etc. The EH68 can keep a rolling 8 hour buffer in the Pause Live TV mode, but if you want to record something or store what you are watching for longer than 8 hours you need to exit Pause Live TV mode and then push the record button.
In comparision to the Philips where it keeps a continous buffer of up to 6 hours and is always in Live Pause mode. If you would like to save what you are watching, you can rewind to the start point and press the record button to have the program saved on the hard drive.
I found this feature most useful when watching music videos, if I come across one I like and haven't seen before, I can rewind it and keep it for later, but with the EH68 I have to make a conscious decision to tape music videos and then go throgh and edit undesirables out.
The MySkyHDi Box also has a continous buffer although I'm not sure of how large it is, but both Philips and Sky Box clear their buffers when you change the channel.