SimplePress Incompatibility with Site Search and Directory

I understand this may be beyond the scope of support for these forums, so I don't expect any miracles. But any information that can help us get a couple Premium plugins to play nice with SimplePress forums would be greatly appreciated.

Issue: Installation of either the Global Site Search, or Blogs Directory plugin causes 404 errors an all SimplePress forum sub-pages. For instance, domain.tld/forums will load fine, but all domain.tld/forums/topic/ pages will throw the 404. Remove these plugins and forums function perfectly again. I have confirmed this issue is not theme related and have Blogs Directory running on our dev install if anyone cares to see the problem in action.

Here is feedback I've received from the SPF Developers...

are those plugins altering rewrite rules? we simply add our rewrite rules to the wp rules… or are they adding new 'pages' in the middle of the url?
our rewrite rules are done in a single location… file sf-loader-global.php in routine sfg_set_rewrite_rules()
we will be happy to work with these folks if they have any suggestions

Thanks in advance to anyone who can provide answers to their questions, or any other feedback that will help us troubleshoot the incompatibility.