I previously owned a DMR2i before picking up the DMR2 pro here on the EE and between the two was a big difference in glass quality IMO. I had paid around the $1900 mark after taxes for it and honestly I was a little disappointed with it at that price. That being said it tracked flawlessly and had no issues with it.
Hearing what Bushnell claims for the new DMR3 is they use a different lens coating and gain an extra 2% light transmission over the DMR2 pro. Is that enough for me to switch no, but the new reticle and parallax down the 25yards are definitely a big plus and I would swap to have those features. Also the bold white numbering on the DMR3 I think stands out better.