Your Merino socks soaking up lots of water, means that they do a good job wicking, which is what you want against your skin. I would say that your Goretex boots were the problem, since once the water entered, it had no way of escaping. I hiked 15 painful miles on the Lost coast in soaked Goretex boots... You said you are looking for summer weight socks; in my opinion a thin Merino would be the right weight and once you have breathable shoes, if they get wet, they should actually keep the moisture a bit away from your feet. I do fine in thicker wool in the summer, as long as I tighten my shoes enough. The thickness of the wool allows for water to be kept even further away from the skin.
I am biased ,though, I really love wool.