Frankly I think that the bigger decision is the one you’ve already made, namely to invest a bit more money in a good set of merino layers that will last for a long time, give great wear and be a lot more pleasant after a couple of days out on the trail. I think the choice between Icebreaker vs Smartwool is in fact largely personal, but here’s some pointers (Updated – I’m begining to lean more towards Smartwool having been using their stuff a lot more after almost 5 years of slavish devotion to Icebreaker – and I think that Smartwool may be a bit longer-lasting).
Smartwool and Icebreaker are both expensive
There isn’t much difference between the two on this front. You’ll pay a lot for either of them. Partly this is to do with the fact that they are made from top quality materials. But there is also a fair bit of branding and marketing going on here. You can also buy other good quality merino base layers from small Scandinavian or Swiss manufacturers for about a 30%-50% less than you would pay for Smartwool or Icebreaker. The smaller companies just don’t have the marketing or distribution reach of the big ones but it is not to say their clothes are less good. They will just be less fashionable yet have kept thousands of Swedes, Fins and Norwegians warm over the years. Also remember you will easily be paying twice as much for merino wool as you would for synthetic base layers.
Fit and style
A lot of people prefer the slim fit of Icebreaker merino. Their tops are generally quite close fitting and are also made with an eye to style. Icebreaker has put a lot of money into researching techniques for printing patterns on merino wool and it shows (see the picture above). That said some people don’t like the prominent logo on Icebreaker. It is not all style over substance though. Many tops have good drop tails to tuck in and keep your lower back warm. A lot of people also like the thumb loops on some of their tops. These are great as they help cover the vulnerable wrist and a bit of the back of your hand for warmth.
Comfort of Smartwool vs Icebreaker
If people prefer the fit of Icebreaker they often prefer the comfort of Smartwool. A lot of people find the wool to be slightly softer and less itchy. Smartwool also has better seams that lie flat and are more comfortable.
Durability of Smartwool and Icebreaker merino
I don’t think there is a huge difference here. Both are made of good quality material. You need to remember to be careful when washing them and you need to not make the mistake I made, which is to let moths into the drawer or you’ll find your wool tops a bit holier than before.(Updated – as I mentioned above, my Icebreaker tops and baselayers are looking quite ragged – admittedly they have given good service over many years – but I’ve been using Smartwool baselayers for the past few months and think that I am now a convert as they feel really durable and are also comfortable).