I can't test CF for the moment, and that's why I simply have to ask.
Somewhere here I saw that CF supports Friendly URLs, and this is fine. But in terms of SEO, how good is CF? Have you tested it very well? Do you use Google Webmaster tools for this forum here to see how is performing for Google?
Very important in SEO performance are the URLs and the content. In no way a forum should generete more than one URL for one content. If it does this it is very bad. Does CF support Canonical Tags? If not, it should!
When the system rewrite the URLs (for the friendly ones) the not-friendly ones should disappear. And, Keywords, description, titles are very important too. And not only those for the main site, but for every category, topic and user.

On-Page SEO Checklist:

Always start with keyword selection, research and testing
Meta Description tag
ALT tags
H1 tags
URL structure
Internal linking strategy
Content
Keyword density
Site maps, both XML and user facing
Usability and accessibility
Track target keywords
Expect results in 6-12 months
Avoid common on-page SEO mistakes such as:

Duplicate content
URL variants of the same pages
Off-site images and content on-site
Duplicate title tags

• See more at: http://www.directtrafficmedia.co.uk/blog/on-page-seo-vs.-off-page-optimisation#sthash.qC9y6WQd.dpuf

http://moz.com/learn/seo/on-page-factors

although codoforum uses a lot of AJAX, we have made sure SEO is not neglected.
SEF is available http://codoforum.com/documentation/configuration

we checked the performace, we used to use drupal forums earlier as the website itself is built on drupal, currently our search engine traffic has increased a lot and most of it is because of this forum.

Does CF support Canonical Tags? If not, it should!

yes it will be