Just to check, will that modification just post new threads, rather than new posts? If so, I'll add that line of code tomorrow and de-select the What's New option for all forums that I don't want to include in RSS.
Well it's supposed to be the responsibility of the RSS reader to know which items it has already posted. But several people have reported problems with Facebook and Twitter reposting threads over and over. Supposedly those code edits fix the problem by sorting the RSS items by thread creation date instead of last post date.