Peregrina2000 nailed it with her review of the Ferrino Trekker. I concur wholeheartedly. That is why I sold it after completing my first
Camino Frances in 2013. It was a fine raincoat, but caused me to sweat so much that even on a cold day, dehydration was a consideration. In the evening, I would reverse the jacket and rinse it in a shower to get the salt off. Hung somewhere, reversed, it was always dry by the next morning.
On my second
Camino Frances in 2014, I found the S2S sil nylon tarp poncho worked as at least as well to shield from the rain that was falling, was better than the Ferrino at being more ventilated, and weighed far less. I had a light blue one. That color contrasted with my surroundings, making me more visible to oncoming traffic while road walking.
This year, for my shorter walk from Porto to Sanitago in April, I used the new version of the S2S. It is even lighter than the earlier version and packs VERY small. However, the fabric is relatively more delicate, so you must be careful of pokes and snags.
Both S2S ponchos share the same, serious design defect. The snaps are too flimsy and come apart with the slightest tension placed on them. After my 2014
Camino Frances, I used super glue to permanently connect the snaps. Hold them together with clothes pins until the glue bonds fully. The likelihood of ever needing the poncho as a tarp is nil on most Camino routes. So, this was a carefully considered decision.
In fact, when I received my new version S2S poncho, I glued the snaps together BEFORE my April 2015 Camino. I had no problems with the snaps. The poncho did what it was supposed to do, protect me and my rucksack from the rain, and it was so small that it resided in one of my rucksack's side mesh pockets. The new S2S poncho is abut the size of a small mango. I do not use these pockets for water bottles. They ride up front on my chest, hanging from the shoulder strap and rucksack harness.
I recommend the newest, lighter, version of the S2S tarp poncho. It is NOT cheap, about USD 85. But it is effective and very Camino-friendly. If super-gluing the snaps together gives you pause, consider using a narrow piece of duck tape instead.
I hope this helps.