If people here sell their signatures for a quite decent amount of money, i guess they do. Don't have any factual proofs though.
I do not think they help as much as people think. They do help get site spidered but not much as far as Pr
Yes, it does. Not much, but yes, it does make a difference. But more importantly, you get a lot of targeted traffic for your site.
with a 4 digit number orf posts I have no fact nor evidence that DP forum sig links are of any use related to serps nor PR but they are useful to announce new sections of a site. since the more links are in the web pointing to a new article or chapter the faster G and other SE may find that news. as to the value of additional traffic from DP forum ... a single good blog post in my blog brings more monthly traffic than 1000+ forum posts here. above all a forum is a SERVICE to those needing fast and accurate help or advice. that is the true value of DP forum.
That is good but for example if you are not in a very high competitive keyword business that can influence from top 30 to top 20
Every bit helps. And if your site is webmaster related, you may get some decent traffic from people clicking on your link.
IMO.. sigs can influence SERPs. most specially using your anchor text to your site/link. and it can get more weight if its related, due to calculated relevance
I never click signature links, much prefer google search to find a relevant search. I kinda messed up though because I sold my signature links when I had like 200 posts permanently for $25 each!
About serps, i dont have any true evidence, but as for target traffic i do. I get a lot of traffic from DP forums.