We have done a new test where all pouches have been hanging out for 5 days in light and heavy rain = “2%” with rain over those 5 days. Pouches has not been used, only hanging (sometimes some wind came). If the pouch was used during the first impression test, it will be difficult to say where the weakness is. When the pouches are hanging (no movement on the pouch), you will see better where the water is and where it has gone. We added some paper under the zip just to see if the zip really was that good to protect from the rain 
Water-repellent zip really doesn’t work good enough, after x minutes in rain, water goes true the zip “fabric” and the stiches on the pouch.
Waterproof zip is “50%” better then water-repellent zip. The zip is waterproof, but not the stiches on the pouch, water leaks in with time (like that why have waterproof zip when the pouch is not waterproof?). If you want a waterproof pouch, it has to be done with taped seams like on a Gore-Tex jacket were all seams a taped for that reason.
Upside down zip has minimum or no purpose in the end. The story goes after Afghanistan and problems with “zip pouches” were there was a lot of sand coming in. A better solution was made with turning the zip upside down to close/protect the zip better for sand to enter (we also did a lot of testing, but the sand beats you…). But if you study the effect is has, its not much, since the zip is constructed to be with the zip out. When you have upside down zip and you bend it, you will see the fabric opens like a door and sand still comes in…
Then, almost everybody adds two sliders to the zip for easier position for opening, but with two sliders, you also make a big hole between them were sand or rain can enter.
Zip edge/cover has minimum effect, the rain will go under it and guide it to the zip very fast and concentrate it to the zip the whole time.
In the end; all kit you bring in the filed has to withstand water or be packed waterproof. Like that there is no need for a waterproof pouch or rucksack, except those who like to swim, but that is a totally different story.
Only important is to have good drainage on the pouch, what comes in – has to go out. We are now upgrading our Laser Cut products with new smart drainage hole, its cut like a cross for incoming protection and normal drainage. 
