While neither may be perfect, the Office Live Site Designer does offer some advantages that you might want to consider before deciding to use a third party designer such as Expressions or Dreamweaver.
First off if you enable third party tools, you will no longer be able to use the Business Application as a backend for you website. You can still use the Business Applications, you just will not be able to collect or publish data to your website. The same also goes for the Contact Manager.
As far as coding and design goes, you can achieve just about anything you want with the Site Designer with a little coding knowledge and by enabling Advanced Design Features. True you can create more XHTML compliant code if you know how and use a third party designer, but so far I have not seen an instance where some Office Lives’ coding flaws have caused major problems, or caused a serious limitation.
Finally, as far as search engine optimization (SEO) goes, the Site Designer does just as well if not better than third party designed sites. Even though you cannot add h1-h6 and alt tags. You will of course want to make sure you properly optimize each every page on your site, with keywords, descriptions, and titles. It would also be a wise idea to limit the use of the HTML module or combine all your code for a page into one HTML module.
