Con's to having a professional portfolio would have to be that we do not know what other people think of our page. Or if possible employers are going through our portfolio and they think it is to professional and they do not see the fun side of us. Also vice-versa if the employer thinks that our page is to private or to simple and it does not market us as a professional we may be out of the job.
The pro's to a personal web site are that we may give it a bit of everything personal life, professional life, and our affiliated companies or things we like to do our spear time. We may not only have all professional people following us, it may also be friends and family.
Con's to having a personal web site are that having friends and family on the page would be some of the comments that they might post on your page. Maybe there are comments that are inappropriate for employers to see. But the worst would be friends or family posting an inappropriate picture on the page and the possible employers see them and the job is lost.
The pro's to having a LinkedIn are having the people that you graduated with or people from an internship that you have previously worked in. There is also the options to fill in every college or universities that we have attended. This way the page will find anyone that has attended the schools that you have. This way we may stay in touch and find new or current positions (jobs) that are open or opening up soon.
The con's I don't think there are any con's to this kind of method, well at least not for I.