In regard to the question, "How well are product items search engine optimised?"
Our SEO is very good... a perfect balance of easy to update, while
Google mainly cares about the meta title... not the meta desc/keywords... Left most meta title is important for inner pages... so this is where we put the product title. eg
Meta Title = Product Title + Website Meta Title
Meta Description and Meta Keywords are controllable at a "menu button" page level. eg the entire shopping cart will have the same keywords..
or you can split categories into different shopping carts, so they can have different keywords...
Or you can create individual "single design pages" for absolutely each and every product, category, etc... each page will then be linked with a BUY button back into the shopping cart for the actual purchasing only. This requires significant maintenance and double entry of information.
The latter option is really a waste of time... If you have too many products, the SEO of all of them will be "diluted" by their shear insignificance within the entire website... If you want to maximum SEO for a product, then you would dedicate 1 website or domain to just that single product, or alternatively, if you have lots of products, you may dedicate a few pages to your leading products, maximise their SEO, while allowing the catalogue to be lost in the system so to speak... optional extras...
think about supermarkets and the term "loss leaders"...(the products discounted below trade purchase price in order to get people into the supermarket) loss leaders are the SEO products.. the "marketed" products, that get someone into the shop... once in the shop, it is a user navigational experience that matters... not the SEO of each and every single product.
But irrespective.... search google for "TF5000PVRt" ... This a product sold by lots of people worldwide, but our customer freetv.co.nz is 7th out of 35000 pages on the topic.
Or search "Enhance magazine", and our "retailer" emags.co.nz is 3rd from the top.... only behind the actual magazine itself... so our SEO is good!
Each of those customers have more than 50 products each, so dilution has had no effect.