Danny,

I think you’re misinformed. Just because you index the messages and send them a sitemap doesn’t prevent or detract Google’s own spiders from surfing and indexing your site as you indicated. The new static pages will make it easier for Google’s own spiders to get the site because they have problems with dynamics...the old use of dynamics is part of the reason why fewer individual search results occurred in the past (the spiders want unique urls and have to cut off after a certain point--obviously some get through, but many don’t).

This is directly from Google on the sitemap/index issue:

https://www.google.com/webmasters/sitemaps/docs/en/about.html

If your site has dynamic content or pages that aren’t easily discovered
by
following links, you can use a Sitemap file to provide information
about the
pages on your site. This helps the spiders know what URLs are available
on
your site and about how often they change.

A Sitemap provides an additional view into your site (just as your home
page
and HTML site map do). This program does not replace our normal methods
of
crawling the web. Google still searches and indexes your sites the same
way
it has done in the past whether or not you use this program. A Sitemap
simply gives Google additional information that we may not otherwise
discover. Sites are never penalized for using this service. This is a
beta
program, so we cannot make any predictions or guarantees about when or
if
your URLs will be crawled or added to our index. Over time, we expect
both
coverage and time-to-index to improve as we refine our processes and
better
understand webmasters’ needs.

Alison