I currently have a 2012 MBPR with 16gb and 512gb of ram that has served me extremely well. It drives my 20 30 20 PLP monitor setup just fine. I work at home now so I just need a desktop. I plan on picking up MBA 11 to use as a netbook when I am on the go. I want to get it setup so I can run Android emulators etc on my desktop over the network when I am out on my MBA.
The only problem with laptop is the small screen and it's harder (/more expensive) to do a multi-monitor setup. I don't know how people are listing an 11" laptop to do any dev work. I guess if its just a straight editor and not an IDE that works.