@afre and @paperdigits I’ve defintely gotten spoiled with my 3.2 lb Acer 720! Having had 7 lb spec’ed out laptops for years, traveling with a thin and light computer has been a revelation. I travel a lot, so portability and long battery life is at the top of my list.
I do love thinkpads, and I used to use them myself for years (first one bought back in 1999, actually!). In fact, I bought my wife a ~$500 ThinkPad E-series last year, and it’s great. Great display, good battery life, fast processor, etc., and right on price point. But these more affordable ones are just so freekin massive that I can’t fathom it for myself. It’s fin for her since she just uses it at home, but “portable” is not really what I would call it. Their ultrabooks are portable, and are drool-worthy for sure, but cost upwards of $1k.
They did have a good compromise in the Thinkpad 13, but it is not currently available. The X270 (current version of your X220) looks pretty darn good, and weighs in just under 3 lbs. It l comes in at ~$800 at minimum configuration, but the IPS display puts it over ~$1200. 
One potential solution might be their forthcoming A series that finds savings in using AMD procs. The specs aren’s massively better than the Chromebooks in the same pricepoint, however.
BTW How is linux kernel support for Lenovo devices these days?
Oh, and while I agree that an external monitor is needed for real photo edits, I still think that laptop needs a display good enough to edit with “on the go.”