Use the search at the bottom of this page ("ask laptop") and read all the previous submissions. You get quicker answers and HN gets fewer duplicate discussions.
Oh - and buy a cheap netbook for when you're traveling somewhere you might have your main machine lost, stolen, or destroyed.
And encrypt the disk on all your laptops.
This makes your laptop disposable and you can get the cheapest hardware and be fine...You'll never lose work due to your laptop failing on you and you don't have to worry about people accessing your data.
If/when a retina MacBook Air comes out, that will likely replace the 13" MBP.
I have a second-generation Lenovo X100e (so the dual-core processor) and I couldn't be happier. A $45 upgrade to an SSD and $10 for an AGN wireless card saved me from having to spend ~$2-3k on an MBP.
Pretty awesome for what was basically a (high-end) netbook.
Cool as a cucumber in the console and with Fluxbox running and browsers & Sumatra open.
For portability, get a MacBook Air 11", for a powerhouse get a Retina MacBook Pro 15". If you want something in between get the Retina MacBook Pro 13".
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.