I just wanted to share that I've started working to convert the Flutter Basic and Pro to KiCAD.
It's still in progress, but the Eagle file conversion is complete and I've started fixing some of the conversion issues inside KiCAD. The copper generated from KiCAD is pretty close to the original Eagle copper, so it's in pretty good shape.
I'm still learning KiCAD but that's going well. The plan is that once I've shipped all the Flutter Basics and Pros I have from this batch, I can fab a new batch with the battery charger fix. I need to double check, but I believe the Eagle files already had the battery fix when I converted them, so beyond some thorough testing that fix I think is already applied.
See the files and fork them here: