Thanks for clearing that up. So far I have not run into any problems but I have only made a test application with it (part of the sdk which I plan to release with SE) and it hasn't crashed. Bushing did tell me long before I started using Mac hardware that the drivers were not very good and I trust him when it comes to anything related to Mac stuff.
I shall set up libftdi and give it a try.
btw isn't VCP only USB 1.1 spec, i.e can't handle a 64K down packet?
Well, I am not sure if d2xx is supported correctly. Basically I do not have a Mac personally, I was talking to 2 Team Twiizers back then and they literally complained about the official ftdi driver for being hardly supported, slow and unreliable (meaning it sometimes crashes). The major downside of it: rather than supporting to be a Virtual COM Port or a D2XX library at once you can choose one of both - D2XX outrules the COM port and vice versa.
As far as I can see libftdi is its own implementation: so libftdi is not 100% D2XX compliant and not 100% COM Port either. Internally libftdi uses libusb and directly communicated via USB.
@giantpune: your code seems interesting!