I bought a D2 and am currently using my D1 while my D2 sits on my desk.
My girlfriend has a HTC Desire (very similar to a Nexus One) and every time I use it, I realize how much better it runs than my D2. I figured this was due to two things: the Snapdragon processor and/or the lack of MotoBlur (which is horrible IMO compared to HTC Sense) and VZW bloatware.
I rooted the D2 and tried both Tranquility and Epic roms (the only two roms for the D2). Both were an improvement performance wise, but unfortunately were buggy and crashed on a regular basis, not to mention neither one fully removed MotoBlur. I find that stock Android does everything a phone should/could do better than MotoBlur without all the BS running in the background slowing the phone down. I would overclock the phone but Motorola kaboshed that with the lovely eFuse that bricks the phone if the bootloader/kernel are modified/changed.
At this point I'm back to using my D1 which, running CyanogenMod and overclocked to 1100mhz, runs 10x better than my D2 in pretty much every way. Forum member slayher is currently working to get plain AOSP running on the D2 and when it's finished, I plan to give my D2 another chance because I could use the extra RAM and the keyboard is worlds better.
I bought Motorola Droids because I like the physical keyboards but I have been making it a point to practice/get used to the virtual keyboard so that when it comes time for me to upgrade again, I can ditch Motorola altogether and get an HTC phone. If there was an HTC Evo clone on Verizon when I bought my D2, I would have bought it instead. Snapdragon processor and no eFuse? Done deal.