well bonapartist, let me start by saying that when people mention degregation i think 99% of them are refering to information they read in rob clarkes book HASHISH. In his book he talks about some tests that were run for degregation using third world imported hash. They found the thc percentages to drop quite a bit each year, having had pressed the hash, this ruptures the wax membranes , which makes it easier for oxygen and light to work its magic. HOwever these hash's were of fairly low thc already. I dont think you can apply the same logic to the hash we make now adays that is 30 to 60% thc depending on your tools and starting materials. I know i have personaly smoked 14 year old dry sift that was full melt, and it got me wicked high> No doubt about it.
I dont think nepaly or indian could compare on the same level> If you smoked 14 year old indian charas, you would see much like i have ( i've smoked 12 year old stuff), it had little to no affect.

Now to address something else you mentioned in your question> The pressing of wet hash> doesnt ruin the hash because it ruptures the wax membranes, but because it allows the moisture that is still present to contaiminate the precious oils and cannabinoid profile that resides inside. The worst thing you can do is press wet bubble. Such a pity to come so close to having perfect hash, and then ruin it at the end.
Hope that helps.

peace
Bubble man