Is 301 the correct redirect code for "fake" subdomains?

My site assigns each user a fake subdomain along the lines of

http://username.mysite.com/ 

which redirects to

http://mysite.com/shop/username

The second link is the one used internally, is assigned as link rel="canonical", and what I want to display in the browser as the correct url, the subdomain is basically just a convenience for my u开发者_如何学Csers.

The question is whether 301 is appropriate in this scenario? A 301 redirect is used for a link that now points elsewhere permenantly, which implies that the old link is deprecated. My concern is that I will attract bad SEO juju by using a 301 redirect whilst still advocating / promoting the use of the old link.

Yes, 301 is the correct choice here as search engines will index the final URL rather than the subdomain. I've never heard of any penalty for having too many 301 redirects. Other redirect types less accurately described what you're looking for (temporarily moved, etc.).