Multiple Domains - SEO benefits/concerns

Currently, the website I'm managing has 1,000's of pages.

The reason being is that we have 100's or products. These products have various styles, options, hardware, options, testing results, etc, which all are lengthy and require thier own pages.

For some of our products, we rank very high in search engines and for others, we struggle (even though we spend a healthy amount on ppc) and have unique/detailed content on these pages.

Recently, we have been toying with the idea of splitting the site into 5 different sites. We would keep our main page, which would list all of our products and provide basic information on the main products.

Then the 5 main catagories of these products would have their own domains, for example: CompanyDoors.com , CompanyGreenhouses.com, CompanySunrooms.com, etc.

Having original content would not be a problem and no dublicate content would take place.

I've read a few articles statin that this isn't a good idea, except in certain circumstances. --- Any thoughts?