Can anyone explain the value of having a link on a low PR page on a High PR site? Profile links are popular but how much value do such links have?
Yes , It has good value. If you get a link from a PR0 page of a PR7 or PR8 site then that link is obviously a good link. high PR site means authority site and a link from a authority site is always fetches good value to your site.
Any followed link you get will help your website. Don't think much about how much it will help, if you are getting anything free of cost then go for it. More the PR of the page from where you are getting a link is the most valued...
Both are links but search engine likes high page rank links. Because if your website get high page rank back links so it will also help in increasing page rank.
It means the pr might rise in PR over time, so if you built - Say 20 links to it, you could have a link on a pr2 page quickliy
OBT also matters If a pr2 Site have 30 OBT and a PR4 site Have 150 OBT then PR2 will be more power full.
High PR usually stands for authority, thus if SE's see links to your website from high PR websites they'll assume your site is authority as well. Plain and simple.