Welcome to the Q&A Forum

Thanks very much for the great answer Andy.  Really appreciate it.

Regarding the sub-domain versus separate domain route, it was a hard decision.  We want each of the four websites to feel like definitive specialist businesses, and in that case treat the 'main website' as more of a 'corporate site/main site'.  I guess it could be regarded that each website could almost be 'sold off' as a separate business.  i understanding your comments about strengthening the brand.  All the url have our main name as part of the url, and our logo is on each site, along with a different colour scheme.  or did you mean more that Google will give much more punch to the subdomain option?

The information in your google webmasters link about canonicals is from 2009, and very informative and relevent.. I guess it is still current?  The main website of the group has about 10000 different products on it, and each product/sku has a different url. Would this mean that i would have to create a canonical for up nearly 10000 entries x 4 websites, back to a preferred url?  Can I instead do Product Category urls?  (i would love the option to send the category "Bandages" to the healthcare site by canonicals, even though it is on 3 of the sites)

Is there an efficient way to do the canonical in bulk?  or should i just concentrate on the top selling products? What penalties could apply because i don't manage to get them all done in a timely manner?

Thanks in Advance!!

Is there a solution to our situation without getting bad duplicate content penalties? or on balance, is it worth risking some duplicate content penalties?

We are about to launch 5 multistores with almost the same products on each store, but with different videos/news etc.  (www.nopcommerce.com)

Our goal was not to increase google exposure, but to be specialists in the industries.   So that Foodservice customers can have a 'foodservice' experience on the FOODSERVICE webstore, and see a unique foodservice blog and foodservice videos (and likewise the HEALTHCARE, INDUSTRIAL, FACILITIES sites).  The main store will have all the products on it. The multistoreS will each have about half the products.

Can you clarify if the panda will actually drop rankings on ALL our stores, if we have 5 stores with duplicate content?  Would it be WORSE, having 5, than having 1?

How would using canonical tags affect this outcome?  Can they be applied per category?

ANOTHER QUESTION:

For getting google results to land on the correct ministore/multistore:   (ie making industrial product searches land on the INDUSTRIAL STORE even though they exist on several stores):  Would the canonical tags help with this too?