Seriously...
When I had the LCD-3's here they did everything the DT880's did and them some in Spades, the bass was luscious!
So yes indeed eveyone who owns the DT880's owes it to themselves to listen to a higher tier headphone to find out what your missing...
Well, I'd certainly expect the LCD-3 to ace the DT880 given the respective prices. No surprises there.
As to whether we owe it to ourselves to listen to higher tier headphones, I've already owned the LCD-2 (Rev1) and HE-500 (twice) and am still quite happy to stick with the 880. The LCD-2 was just too damn heavy and unwieldy, and the HE-500 I just didn't like the sound of, period (plus it was also too damn heavy). A truly satisfying headphone is really a combination of several factors, comfort and build quality (reliability) being not the least of them, so while it's true there may be better sounding phones in existence, for me the 880 hits the spot in so many areas I feel I'm not likely to soon find a satisfactory replacement.
Let's list them:
1. It's amazingly cheap. I think even its detractors would agree that the price it often goes for (under $250) is ridiculous for what is in fact a genuine alternative to the HD650 (albeit a different flavour).
2. It's hugely comfortable. Without comfort, sound quality means nothing.
3. Good build quality. Certainly nothing cheap about the build quality.
4. Comes in different impedances to suit purpose. No other manufacturer offers that.
5. Can be custom sprayed for a zippo look. No other manufacturer offers that.
The last advantage isn't really something you can list, but arises out of its one major fault: the peak at 6.5khz. All headphones, at least all affordable ones, have a fault; the important thing is how easy it is to fix. Some, like the lower treble peak in the AKG K7--s, are quite difficult without proper EQ. The DT880's, at least subjectively, can be virtually eliminated with a simple tone control. It may not be scientific, but it works.