Yellow_Sun - 1:03 am on Jul 27, 2010 (gmt 0)
In my findings I have noticed #1 to be the most truthful, and maybe #4 if I am understanding you correctly, of the four you listed and can provide you an example of my experience on this topic.
We have an aged domain that had competitive keywords ranking #5-#8. We stopped getting new links for the site, and over the next 5-6 months those same competitive keyword rankings went to #1-#4, basically each went up 3-4 spots. We made no changes during that period, and I feel the aging of links kept kicking in for the better rankings.
The SEO experts at your conference may disagree, and if so, it might be because the sites to which they have their aged links on have completely gone down in value, which is maybe what you were saying on #4.
Lets say a link is ranked on a scale 1-10 for value, 10 being the best. If Site ABC has 100 links each at a 10, and 2 years later those same 100 links are now 50 at a 10 and 50 at a 5, your value easily could down, and will in my opinion, because of this although the links are aged.
I don't agree with #2. As for #3, it's easy to think the link is most powerful when first found, "freshness obsession", because they are seeing immediate results, which you should when you get a backlink.
Again, this is just my opinion and what I have observed. This is a great topic and very important.