I own the OMM Kamleika trousers, the older model. They are stretchy wateproof, but fit is very important, the effort to raise your leg can be made worse if your stretching the fabric due to poor fit. Remember that anything you add to the legs to make it harder to walk will obviously tire you quicker. I do a lot of cycling and my calves are about the size of most people's thighs. I had to go and try some on to know my size.
Point was made that when it starts raining temperature remains the same. Kind of, it depends on the season. In UK winter, the rain is coming with an increased temperature, the dry is often colder. In summer, the opposite. The effect with over-trousers is the chilling effect of rain hitting the fabric is held away from your legs and you're effectively becoming too-warm and often get as wet in waterproof over-trousers as just some more breathable windproofs. Also, its not just the rain hitting the legs, but the rain running off the jacket which is effectively doubling or more the water that hits the crotch and thigh area, these becoming soaked if you're not in something to shed runoff.
I liked the OMM for cycling cold wet weather, but breathability not brilliant. For walking, when its not sufficiently cold for Paramo, I found a good compromise, is for water-tolerant trousers, such as Rohan poly-cotton and carry Pertex over-trousers to wear if rain becomes too heavy, to reduce the run-off soaking in. Areas like the rear of the trousers and the lower legs are bone dry often.
For when its properly cold forecast and/or pouring down for hours, also to-be owner of Velez trousers, I loved my Cascadas but they limited by too-warm and I had a gap of a temperature betwen the above OMM / Pertex and Cascadas. I paid a little under 100ukp for my Velez trousers, I hope to sell my Cascadas for around the 60ukp, probably in the new year as prices increase, so the upgrade costing me about 40ukp.
