endemicity on "adding a domain through WP.com"

Hi,

I'm considering purchasing a domain name through wordpress.com and mapping it to my site (also hosted at wordpress.com).

Will this new domain alter my RSS feed url or otherwise disrupt traffic? For example, when someone types in anthozoa.wordpress.com (my current URL), will they be directed to unchartedatolls.com (what I may rename the url to)?

I like the option, but I'd just like to know any potentially negative effects in terms of people's bookmarks, RSS feeds, etc.

Cheers,
Dusty
anthozoa.wordpress.com