A little heads up for you...The Patagonia Capilene 2 has extra seams that run from front to back over the middle of the shoulders, which are absent in the Capilene 1, and when using a backpack, the weight of the shoulder straps will press onto these additional seams, making the Capilene 2 more uncomfortable to wear when hiking than the Capilene 1.
Usually, the lighter the hiking equipment is, the more expensive it is but although the Capilene 1 is a lot lighter than the Capilene 2 (80g vs 148g) it's actually about 10 Dollars cheaper!
The main problem with either Capilene is that they do not offer the wearer much sun protection...Only SPF 15-20.
After much research I went for the ultralight Rab Interval instead...It's 2g lighter than the Capilene 1, yet manages to offer SPF 35+ sun protection, and its about 10 dollars cheaper than the Capilene 1 (about £20 cheaper than the Capilene 2), so you can buy 2 Rab Intervals for the price of one Capilene 2!