If you just turn on the HDR and it is not recording anything or about to record something why does it stop you viewing the current channel while it retrieves the guide data?

Does it need both tuners?, the none HDR models do not or is there some other reason?

Automan.

Pressing guide downloads a complete new guide from the home transponder on Eurobird 1 so steals the tuner for up to 30 sec. You can access the buffered epg at any time without requiring a tuner, just press schedule and then red

Why can't it use the other tuner or does it not have the required signal processing circuits to extract the data?

Automan.

Not absolutely sure why not except to say that the only tuner guaranteed to be available is the one that you are using. Factor in the possible ways the hdr can be used on say 1 cable in this mode the second tuner would only be able to access the guide if the first tuner happened to be using a low band horizontal transponder.

What's wrong with using the buffered epg ?

Perhaps it's the case that, since there are clearly situations in which it's not possible to carry on with the sound of the current channel, it's more straightforward to decide that it should never happen.

The alternative is to have the sound sometimes continuing, and sometimes not. While some users may be happy with that, quite a few would probably worry that something was wrong, and complain that the unit was faulty. If that happened a lot, you'd potentially get lots of support calls, or worse returned units.