When I was in Santiago last month I picked up the newest Decathalon poncho, the MT900. It is heavier than the
Altus but has two advances that I appreciated -- (a) there are slits where one would normally have pockets that allows you to reach in and get something (like money or your credential) from a waistbag or pocket without unzipping or pulling it up and (b) it has long zippers under the arms to provide air circulation to avoid the sweaty drip people mention in this thread. It didn't rain much on my walk, but when it did, opening those zippers definitely made a difference.
The only downside for me was that, as a shorter person, even the small size was very long and while it didn't hit the ground if I was on a flat surface, it would do so on any relatively steep grade. It is long in the back to allow for a larger backpack -- unlike the
Altus the additional length doesn't snap up when not in use, or if you have a smaller pack. As a result, I intend to get it hemmed and put in a snap or two to take up the additional length in the rear before I use it again.
You can't get it shipped to the US, and even in Europe it isn't easy to find in the stores. I had to take a cab out to the mega-Decathalon in Santiago to get it -- they didn't have it in the smaller shop that is right in Santiago.