Just lost my post due to session time out ....grrr
So keeping it short.
Move old site to seblod
google has indexes of pages with ?format=feed
Seblod has no view for this (add it to a list view/url and yu will see what i mean) and legacy controller in joomla libraries produces a 500 error because it cannot find the view
Why does this matter? It matters because despite having a branded error page for a sever 500 error, google webmaster tools will report crawl errors on these pages and this can only be bad news for page rank
change error message in joomla library ref:http://www.inqbation.com/change-500-internal-server-error-in-joomla-2-5-to-404-not-found-error/
Seblod to provide standard rss views in list models