I think another use case would be where I access a blog article from an RSS feed, and the link contains something like www.foo.com/blog/post/1?rss=1; which I'll accidentally bookmark. What I really wanted to bookmark was www.foo.com/blog/post/1.

My advice for the development team would be to allow users to change the URL, but drop annotations/highlights for the page. Alert users with a pop-up, "You are changing the URL for this entry. YOU WILL LOSE ALL SAVED HIGHLIGHTS AND STICKY NOTES! Are you sure you wish to proceed? [Change URL] [Cancel]"

I find the limit of 10 tags per bookmark arbitrarily restrictive; the limit creates a disadvantage to an otherwise superior social bookmarking service. Please consider removing this limit or placing it at some significantly higher number (e.g. 30 tags). Diigo prides itself on doing more; tagging should not be an exception.

I'd like to add that this essay points out the reasons why you don't want to restrict tag usage of the community:

http://www.shirky.com/writings/ontology_overrated.html

Briefly, you want tags to be associable in order to connect related concepts, but tag distribution has a "long tail". Limiting the tags cuts off this tail, severing many connections between concepts.

I hadn't realized this limit was strictly imposed by the Diigo add-on. Apparently the web interface allows more than 10 tags.

I would like to bring up that there still exists a total character limit for tags, though.