These are amazing. I printed a set, and they work beautifully. It's very easy to take filament out and swap filament, as long as you do it while it's still hot. Last night I managed to print to (almost) the end of a spool and then paused and swapped in a new spool and resumed, something that I couldn't do previously.
That's the same one I ended up using. The spring didn't quite fit into the hole, but it appears to be staying in place anyway. :-)
One thing that struck me is that while the springs are staying, they feel precarious, like they might pop out