Can recording be done using the digital zoom then? If so that's another feature that went over my head with a big whoosh. A friend demonstrated the digital zoom on his 7D when we were observing a barn owl roost from a distance - through his 500 f4 too! It was amazing to be able to see them in the twilight at a considerable distance and I'm sure he said that he couldn't record like that. To be able to record would give me useful data
I think you might be confusing the 5x or 10x magnified live view feature included on most DSLRs as a focussing aid, which as you found out, is also quite useful if you don't happen to have a scope with you.
The 3x-10x zoom on the 600D and new 70D is different because it allows you to record video (but not stills) which as Peter noted, is extremely useful for wildlife watchers.
I recently bought a 600D to use specifically with my Swaro scope for digiscoping as you can get phenomenal magnification with this set up. I connect the scope and camera with a 40mm pancake lens and the DCA digiscoping adapter. As an example, if you have the scope set at 30x mag, and 3x video zoom, you can shoot videos at 90x. The benefit is that the brightness does not suffer as the camera is cropping the sensor instead of optically zooming. Video quality is just about as good up to 5x, but breaks up a little after that. In reality I find that keeping the scope below 40x and the camera below 4x zoom gives more than enough mag for when you need some extreme reach, with sufficient quality to make it worthwhile. That's 160x for videos with the potential to go further if air quality and wind (or lack of!!) allows. I have no idea how that converts to mm, but it's a lot!
I realise that some of the above would be more appropriate in the digiscoping or videoscoping forum, but as the subject was brought up here I thought it might be of interest.
Even with a 400mm lens you can get a very useable 1200mm-2000mm video camera, even if keeping the camera's zoom below 5x. By adding converters you could double this. If this feature is in fact going to be included in the 70D then I agree that it will be an added bonus that is often overlooked in the 600D.
Recently at the UK Bird Fair I asked a Canon rep if this feature would be repeated on any forthcoming bodies, but she seemed to think it was a bit of a gimmick and couldn't give a definite answer. This news, if true, is very welcome to me. I say this because when the EOS-M body was introduced it was rumoured to share this feature with the 600D, but on release the feature was never introduced on that camera.
