I've been musing the use of keyword urls as a method of improving serps by a few more positions upwards...

take the example of a site who uses comanyname.co.uk as their primary url, this great for geting branding awareness, but rubbish for keyword urls.

So to get an extra bump we all know that company.co.uk/shop/keyword.html serves a purpose

but does a subdomain have more weight ie keyword.company.co.uk and use 301 to redirect to a single product page for the keyword (assuming the SPP is already company.co.uk/shop/keyword.html?)

or is the difference negligable? or is it frowned upon?