What enterprise level commenting system do you recommend?

[rmteamseo]

• Must be SEO "compliant".
• User friendly
• Must be customizable
• Possibly extendible

[Bevelwise]

I've never heard of a commenting system described as "enterprise" but a couple that we have used in the past are Disquss and Facebook's commenting engine.  I'm also assuming you mean commenting system as applied to a blog?  The biggest thing for me when it comes to a commenting system for a blog is the crawl ability and user friendly.  From the usability side of things I think it's important that users are not required to make a new login on your system, which is why I recommend both of these because they work off of other systems where users can make accounts and use them all over.  Both of these systems offer some of your advantages, but do not offer the ability to customize the platform.  I see a lot of people who want this going proprietary.

[rmteamseo]

I have not come across any "enterprise" commenting system either, that surprises me because it should exist. I am looking for a system that caters for really large websites.

Disqus and Facebook are good but from a SEO perspective they have no value.