Hey there!
There's no benefit or negative effect of this either way - so there's really nothing to worry about here.
Furthermore, if you type in http://www.consumerbase.com/ you get redirected to the .html version and it's the same for internal pages. This means you've not got any problems with duplicate URLs or content.
In short, everything is in order and from an SEO point of view there's no reason to make the change - all is well! The only reason why you may want to make the change is from a user experience point of view - but I don't think visitors to your site will be concerned with .html extensions at all.
Hope this helps to put your mind at rest!