Following on the announcement from my previous post on this topic Views RSS: Change to preprocess variables? there have been some heavy changes just pushed to 7.x.2-x-dev branch of Views RSS module.
Most importantly, the feed is now generated from one big feed array passed to format_xml_elements() (with new hook_views_rss_feed_alter() called just before), there has been big changes to preprocess functions (with most of them removed), and 2 out of 3 template files has been removed as well (views-view-views-rss-fields.tpl.php and views-view-views-rss-field.tpl.php).
This now needs to be backported to D6 version, and - together with one additional feature I have to add in both versions - will end up as rc3.
Not over over the next several days though I am afraid, as in few hours I am getting off the grid for some Mediterranean diving. Will be back in around a week!