WTS refers to the latest Aksium model which stands for Wheel Tyre System, basically you buy the wheels and get tyres with them now. I have got last years model which apparently are 60g heavier on the rim.
I am happy with the wheels but they did not make the big difference to my bike that I thought/hoped they would. Don't get me wrong they are good, bearings are smooth and free rolling, the wheels look good and feel stiff almost to the point of making he ride on my bike a bit harsher.
It depends what you are upgrading from, I had a pair of Alexrim 500 before which I replaced because of rim wear and a knackered freehub. It turns out that the Alexrims were actually pretty okay but I would always have been wondering had I not bought the Aksiums. I have no regrets buying the Aksiums as I use my bike a lot but beware they may not be a big step up, all depends what you are using at present.