We are currently using an outdated screen scraper gem to import contacts from gmail/yahoo/etc. I want to update this to use the new OAuth based APIs so users don't have to enter their credentials on our site. I'm really intrigued by the work Plaxo is doing with Portable Contacts which Google also supports. It feels like that is a good direction for read-only access, and it is still backed by OAuth.
Are there any compelling reasons to just go with the standard OAuth API for these providers instead of going the Portable Contacts route? I'd like to know if there are strong reasons to avoid it. I'll still be using straight OAuth for the ones that don't support PC so it's not a question of development time, more one of support and confidence in the new approach.