Most of DP thread have pr0 to pr 1. One page has 20 post. One user has 4 links at sig ... You maybe consider spammer from these link farms IMO
ez now... im not sure on the quality of any signature link... i dont think they carry much weight at all... i think the best way to forum link is in content anchor text style... i mean how will a sig link be tied to new content around it.. u kno what i mean..? i mean like the content above the sig link will never change n so i dunno if they carry any weight... perhaps take faith in the fact it might convert into click through... as for your exact question... hmmm not sure mate... peace
A lot of DP threads rank very nicely in the Serp's, so a Sig link has the potential to get you some Organic search traffic
I was about to open a similar thread, asking if someone ever experimented linkbuilding a site using only DP and which results he obtained...anyone?