Robusta Im not sure what advice i can give you, the reason for the feed failing on most people is not because the feed is wrong, but because people have added things that causes HTML tagging to occure. Just for SEO reasons really you should have the short description in anyway, as this will help with keywords in the search results.
BigMac
I havent got around to changing the main file yet with the updated file i released yesterday, i just ran out of time
If you generated a feed before updating it, you will need to genertae another feed again to over write the last one with the new feed.
If you see this code at the top of your page whe it is creating the feed
Warning: fopen(/home/xxxxxx/public_html/mambots/system/vmrss_v4/all_products.xml) [function.fopen]: failed to open stream: Permission denied in /home/xxxxxx/public_html/mambots/system/vmrss_v4.php on line 0
That means the XML file itself is set to have no write permission so it cant overwrite the last feed with the new one, you need to change it to 777 (read and write everybody), and it will work perfect.