Not an answer to your question... instead saying what i would do if I had a lot of small websites that were variants of a single theme....

I would redirect all ten of the satellite sites to food.com and have a huge kickass site there.

I would do that because all of that content and all of those links likes and tweets happening for a single site would make it very powerful and hard to beat.

You will do more damage with a pump shotgun than ten slingshots.

I would close the hotdog stands.

Thanks Robert,

I think that this is a question of weighing an improvement in optimization against a loss of external authority (backlinks from other websites).

If these are brand new pages with no accumulated external authority then there is very little loss in redirecting and a gain in optimization.  That means DO IT NOW - before any valuable external authority accumulates.

However, if there are a lot of external links into these pages then a percentage of that accumulated authority will evaporate through the redirect.   The more powerful these pages, the greater the loss.  In this case the decision to redirect becomes more difficult.  Only google could calculate the value of the improvement in URL optimization compared to the loss of external authority.  If it was my site I would value the external authority much more than changing a url from /toys/ to /chew-toys/

So, I would give two different answers to this question based upon the characteristics of the website webpages involved.

How much ranking power do you think that an optimized URL delivers to a page?  Consider that title tag is enormous, links are enormous..... URL is probably tiny tiny tiny.

Now consider that the authority that these pages carry will pass through your site.

So, if this was my site I would be asking... How much of my external linkjuice is hitting these 20 pages.  If none then I would not expect to lose very much by redirecting the pages.  But if these pages had lots of offsite assets pointing to them the URLs would have to be really fugly before I redirected them.

I am going to respond in two different ways.....

1. If the manufacturing site is sooooo important that you feel compelled to link to it 10,000 times then maybe you should only have one website?

2. If I owned two websites on the same topic I would seriously consider combining them for SEO reasons.  That gives you a single site with all of the strengths of the two sites together.

Clans unite when facing a foe instead of dividing themselves to be conquered.

Thanks!. I am going to look into this.  I'll let you know if I learn anything.

Thanks for all of your input Dr. Pete. The example that you use is almost exactly what I have - hundreds of .pdfs on a fifty page site. These .pdfs rank well in the SERPs, accumulate pagerank, and pass traffic and link value back to the main site through links embedded within the .pdf. The also have natural links from other domains. I don't want to block them or nofollow them butyour suggestion of using header directive sounds pretty good.

@EGOL: Can you expend a bit on your Author suggestion?

I was wondering if there is a way to do rel=author for a pdf document.  I don't know how to do it and don't know if it is possible.