You really can't make that determination without specifying what type of music you're playing and how the rest of the band is tuned.
I have a pair of D2000's which to me are perfect - bass when you need it - not when you don't. I'd be curious to know how these measure. If they have greater gain than the M-80's, then what we're really discussing is the difference between superior and inferior products - bass quantity notwithstanding.
D2000 have about similar bass quantity to it as M80, about 6dB boost or so and yes they are generally concidered superior to M80 as their pricing suggests too (they may have been a bit cheaper in US overall but in europe they cost more like 300 EUR when M80 is more like 180 EUR). Generally speaking the D2000 is often concidered a basshead headphone, recommended towards people with a preference in boosted bass.
Denon's bass is generally softer and deeper skewed which can be see from the more even and lower extending bass than M80's more punchy, more mid-bass focused bass (pointy, curvy shape in the bass that has a peak around the midbass frequencies), I think you may prefer subbass focus over midbass presence. A lot of people dislike midbass, for some it's the opposite, it often comes down to taste as I don't see how one can justifying saying "subbass" is better than "midbass" for example. I prefer evenly balanced midbass vs subbass preference, I'd think for example D2000 would probably have slightly too little midbass versus its subbass for my liking. Many audiophiles tend to also think D2000's bass is a bit on the more loose side, not very well controlled but again it probably comes from the subbass focus (subbass = slower).
Edited by RPGWiZaRD - 7/5/12 at 11:07am