Unfortunately, the latest Yosemite update (OSX) has broken compatibility with my Gen2 stuff!
The PC I borrowed for testing was running Mavericks but with the update it seems my devices are not recognised. It don't think this is a hardware/USB issue as my firmware strictly follows the USB + MSC spec, which leaves the Fat12 File system and OSX's interpretation of it.
I’m working through it now though without the latest Mac OS at my fingertips this could take some time.
If anyone reading this has a mac running Yosemite, is familiar and comfortable in the terminal and wants to score a free Gen2 device, post here!
Or if anyone has experienced USB device werid-ness with Yosemite, It would be good to hear from you too!