Used to be a 15" Matte MBP. Now its a "Mac Pro" with a 23" Apple cinema display. If I'm going to be doing an extraction from a background, I load the image onto my tablet (X61 with Wacom 12" screen)
Hmm... I do the same but with MacPro.
I use a MacMini and Matte screen at home, if I need to use anything onsite it'll be my MacBook.
I don't think the MacMini can cope while with large 10-14Mb RAW files to be honest, it'll be a little too slow for me.
Looks like the question for you is: What is more important, screen size or weight? What can't you live with(out)?
I have a 22" Dell for my tower, the notebook can sacrifice the screen because the lower weight/smaller size is what I must have. If need be, when at home I can have both devices connected to the 22" monitor as it supports multiple connections.
For me, I have a 30" Display in my apartment.. but on the road i'm a bit indecisive about going with the 17" or the more compact and lighter 15"