Travelling Freelancer needs Laptop Advice

I am an intermediate level web developer using PHP and Javascript. I understand the more advanced concepts, but i rarely use them since i generally create fairly standard websites for people (local company sites, portfolios, local charity sites)..

What i want opinion on is this...

I plan to go travelling around asia starting from december. I intend to go slow enough to allow me to pick up small, low-paid web development work that will continue funding my travels (as well as teaching english).

being portable and light, obviously, is important, and since i love dell, it comes down to the following choices. one is much lighter, the other is much more powerful. the lighter one can probably handle my level of coding and basic design work, but how much would i limit myself with such low power?

which would you buy and take with you?

(the light and easy one)
XPS 13
2nd Generation Intel® Core™ i7-2637M processor (1.70 GHz with Turbo Boost 2.0 up to 2.80 GHz)
Intel® HD Graphics 3000
4GB Dual Channel DDR3 1333MHz
256GB Solid State Drive

or

(the more powerful one)
XPS 15
2nd Generation Intel® Core™ i7-2860QM processor (2.50 GHz with Turbo Boost 2.0 up to 3.60 GHz)
Genuine Windows® 7 Ultimate, 64bit, English
8GB Dual Channel DDR3 1333MHz
1TB 5400 RPM SATA Hard Drive
NVIDIA® GeForce® GT 540M 2GB graphics with Optimus

i7, no sign of limits there
for design, I'd go with the biggest screen, some screens are too small to be useful

What's the difference weight wise, there'd be volumetric differences as well to consider

As you'll probably be doing a considerable amount of coding on it, I think the larger the screen the better and to make it practical, I'd go for the XPS15.

Never been that big a fan of XPS laptops though (or Dell laptops in general). Have you thought about a Lenovo ThinkPad instead ?

Odds are "light" is lost when you're carrying around far more than the laptop as you travel. So I'd go for the power and larger screen so it's more useful overall.