As far as
SEO is concerned I know for a fact linked and categorized web sites are more successful within search engines than ones with many products on one page to scroll through. If you have 20 different products listed on one page how should you expect the search engine to rank you for each product name? Of course this wont apply to everyone, but I have a client now that has too many products on one page and is wondering why they are not ranking better for these individual product names. I recommended to separate the products into there own pages linked from a manufacturer or category link page.
To me it just makes more sense to have web sites built in a manor of Index-->Category-->Manufacturer-->Product. It gives the search engines a better idea what each page is supposed to represent as far as a keywords/content is concerned and the end user gets a faster way to find products instead of scrolling.