I have been around OSC and it's clones since 2002. It always been a debate if SEO really works.
The answer is if Google is who you are using SEO for then, No optimizing your tags with a SEO programs does not help much. As meta tags are not weighted very much in the magical algorithm for placement. Other less known search engines meta tags do weigh in a lot more.
Google doesn't use you tags, it extract items from the text on the page. So having Product and category
description longer then one line is a lot more help full, Or using different text for different products.
Many time I see the same descriptions used over and over with only one or two words changed.
Also having a lot of image coming soon's type image hurts your ranking, put up really images with different names.
There is a lot of other things which help as much or more:
1. Doing site feeds/Google site maps.
2. Get listed on dmoz.com, second most used site by search engines for links source
3. Having valid html, and xhtml pages.
4. Having a validated style sheet.
5 Using H type tags more to indicate the priority of areas on a page.
6. Make sure the meta tags you use are used on the page the are used on.
7. Having all products enabled on your site.
8. Not having broken links on your site.
Most SEO now days are designed to assist with at least one of the items above but not all of them.