In most cases I think they would help a bit. I think it would depend on the forum though. Sometimes the only link to your profile is hidden in a javascript drop down menu. In the case of the DP profile link, it does use a drop down but your name is also directly linked to your profile. So the search engines should give you credit for your DP profile link.
Sorry, I've not heard this before - what profile areas (apart from the obvious signature link) should we be changing for SEO???
well.. i think they do.. at least here in DP forum. When I was first registered here, i wasn't allowed to use a signature for a week.., right? But i did about 4 or 5 pst in that first day.. and when I checked te incomming backling the next day with Yahoo Site Explore.. 5 backlinks from DP were there, cause i had my site listed in my profile, NOT in my signature !
If they are dofollow and from authority sites, it will help for sure. Btw, content must be related. You can find most of the big forum ( niche base ) on http://www.big-boards.com. Hope this help.
Surely everywhere you have your link or web address somewhere on the Internet adds some weight or chance of it being crawled so it must have some significance. Unless of course you spam it everywhere and then Google do nasty things to you
It really help a lot specially if the forum will give you unique technique in SEO and also do-follow attribute.