Just wrote a opml checker to test invalid rss feeds for my feedly subscriptions.
The biggest motivation is that 無名小站 was closed at 26 December, 2014.
Most of my friends’ blogs cannot be reached anymore.

Usage:
$ opml-checker feedly.opml

Source Code:
https://github.com/yhchan/opml-checker

Performance:
It analyzes my 510 feeds in 80 seconds.