Where are you?
Both tents you suggest are serious mountain tents and pitch outer first, which is great for a wet climate, but almost non existent in the USA. They are also pretty tight, so you had better be really cosy with your partner. They are both over your suggested limit of 2.5 kilos. You will probably need a free-standing model as the ground tends to be extremely rocky in Iceland. Tying out guys to rocks may be your main method of making it wind resistant.