Ruderic - Elliott -
Not sure if this will help you or if you even want to bother with it. Note: the 0.0 and list didn't have any affect. I removed it all.... BUT....
I found the offending post that caused the error in the RSS Feed.
1) I use posts as a workspace as I build my site
2) I created my home page text using a post (just to work and test formatting)
3) There are a number of short codes and the tooltip etc., in the home page. This post was published
4) When I unpublished this post the RSS feed works
5) Feel free to login to my WP Dashboard and look or grab the code if it helps you trouble shoot. Obviously this isn't a real blog post, but I had been using the post as a scratchpad.
6) I'll keep the post unpublished while I'm testing, but it's called "Home Page Call To Action." Something in this page is causing the Safari and frankly the Firefox error. I don't think anyone would use as many short codes as I used in this "post" so the chances of the replication are probably low. But I thought you should know.
Hope this helps.