I also got 2x DR-2d now. I'm a bit sad that it's not the same speed, but still good to have them
First it was very difficult to me too to match different sounds with different speed, I couldnt make 100% sure if the recorded sound was just a little different.
How I tried to check the speed difference: I put a jack cable to my PC that splits to 2 and recorded 1hr music with both recorders. Trying to check how much to correct with time warp (in %) in audacity/soundforge/goldwave, etc. That's what I did with Edirol R09HR - DR-2d difference too. Much easier to check whether its matched 100% if you compare absolutely the same sound.
If you once have the exact number, dont need to duplicate a source anymore.