Well, if you have that monitor set up where you use your MBP/where you would use that new iMac, I would suggest just connecting the MBP to the monitor and using it as a desktop with a keyboard and mouse that way. Unless you are performing extremely graphics intensive tasks you really won't see a difference you may be upgrading to a slightly faster CPU too but the fact that you have the option to pick up your laptop off sets that.
Well, if you have that monitor set up where you use your MBP/where you would use that new iMac, I would suggest just connecting the MBP to the monitor and using it as a desktop with a keyboard and mouse that way. Unless you are performing extremely graphics intensive tasks you really won't see a difference you may be upgrading to a slightly faster CPU too but the fact that you have the option to pick up your laptop off sets that.
Bingo. I have an iMac, and I just don't want a desktop as a primary workstation. I'm getting a MBP - if I had the money I'd get a TB display but I'm keeping the iMac.