A theory for discusion
Having shot film and now digital, I'd have a different perspective Vaughan.
I think you're currently have a lot of fun with the P880. I like this camera a lot too.
However, I would not use analogies to cassette tape - I used to like analogies but have over the past years, I have found them counter productive. They conjure different perceptions from what the originator intends and that's not helpful to any party.
The DSLR has a brace of features. Some of them are directly attributable to the design of an SLR but some of them are tack-ons - when you discuss the concept of a DSLR with other people, some parties may not distinguish what is directly the result of DSLR design and what is a tack on and applicable to any camera.
Similarly, I emphasise that people not call the P880 a Point and Shoot. The term P&S can often be used in a derogatory way and it describes an intent, not a camera design. If I fit a Nikon D40 with an all-in-one lens, set various hands-free settings, it is a P&S. The term describes intent, not camera architecture.
The P880 is essentially a non DSLR - a viewfinder camera with an EVF and an LCD screen. It has live preview and that live preview is visible via the EVF or the LCD screen. If you want to rig it, you can engineer or fit an OVF onto the P880. But that wouldn't make it a DSLR.
Now, whether the DSLR will "win" or a non-DSLR will "win" - that doesn't matter. What matters is for $X, what can you sell to me. If you engineer live previews into a DSLR like the Oly, you raise the price of an otherwise cheaper body and rob the light from the DSLR sighting mechanism. If you engineer an optical viewfinder onto the P880 body, not just the peephole that you see on the Canon A series cameras, you then have problems with keeping exact parallelism of view when zooming. If you engineer removable lenses on the P880 body, you make it even worse to keep costs down.
So it doesn't matter how you make the camera - you don't want to tie down the engineer and inventor by saying that you should fit live preview to a DSLR to achieve that objective or fit optical viewfinder and removable lenses to a P880 type body to achieve that the same result.
As long as you can give me reputable lenses, clear and reliable sighting mechanism, realistic judgement via an LCD screen with histogram and all that jazz, I don't care how you do it.
In fact, if you fit bluetooth to the P880 class camera and give me a 4"x5" untethered viewfinder / picture frame shaded from direct sun somehow, like those movie cams, I'm happy with that invention too.
'Ancora Imparo - abbiamo tutti qualcosa da imparare'