I did come across one issue – Feed2JS needs you to enter different versions of the url for your blog feed according to whether you are taking the feed from WordPress or from Blogger:
• for a feed from a WordPress blog: (blogurl)/feed
• for a feed from a Blogger blog: (blogurl)/feeds/posts/default?alt=rss
Thanks to Peter @ Enviroman, whose tip came up in a Google search.
Another new thing!