What would be great is if they made the HD releases to seamlessly switch to the original effects shots if you were to choose a different "play" option from the menu!
They've been doing this for a while (on DVD, that is) for old (pre-2005 series) episodes of Doctor Who. Some of the nicest were when they replaced (optionally) the wobbly pie tins on strings with retro black and white CGI flying saucers
Some of the old video composites also get replaced permanently with steadier digital ones.DE