I tried using Delicious but it did not fit the bill well. I now use Firefox Sync, which seamlessly syncs all my bookmarks. I use 'Read it Later' (FF addon) to keep track of my to-read list and Google Reader for about 40-50 RSS feeds. I think the downside is not being able to sync with other browsers (may be there is a Chrome extension for FF Sync??, I am not sure). And I really did not dig the whole social bookmarking thing, I just tweet any interesting link I find.

As for using specific tools, the problem is one cannot be sure if it is going to be supported continuously. Though every tool provides a way to export data if it ever is discontinued, the overhead of finding a new tool and getting used to it is tiresome. So I find it better to stick to the default browser provided tools.