R – Which USB classes are supported driver-free

You're using libusb-win32 as a filter driver; that is, the HidUsb device driver is assigned and loaded for your device, but then the libusb-win32 driver is loaded on top and gives you unobstructed access to the hardware.

If you don't want a HidUsb (or any other class driver) to perform any communication "on your behalf", simply associate libusb-win32 as a device driver with your hardware. For this, you'd have to create an .INF file associating it with the VID/PID/Revision of each USB device. If I recall correctly, libusb-win32 even comes with a utility to generate such .INF files.

If you install this .INF file e.g. with PnpUtil.exe (available on Vista or higher), you might still run into issues where, although you're a better match than the generic HID driver, the HID driver is still selected.

The generic HID driver matches devices by their Compatible IDs (i.e. by a USB interface class) while you'd be matching by Hardware IDs (which have higher priority). However, Windows might give priority to other aspects, such as your driver being unsigned. Read: How Windows Selects Drivers

Luckily, even in that scenario, signing drivers with a self-generated certificate (use CertUtil.exe, MakeCat.exe and SignTool.exe) is not too difficult.

If no driver is needed for your USB device and it the uses 'standard' USB classes then in theory it doesn't matter what VID/PID combination it uses.

However, if another company/device is assigned the same VID/PID combination (doesn't look like DEAD is assigned yet in the company/VID list) and a user wants to use it at the same time as your device or the libraries for the other device are installed on the host computer, then neither device may function correctly.

If the device is a product you may want to look at some of the vendors reselling PIDS rather than making one up. Even if the VID is obsoleted by the USB org (see the list at the bottom of the USB tools page) it will likely remain unused in the future.

[rant on] At $2K, a VID is an incredibly overpriced 2 bytes. I and many others would happily spend a few hundred $ on a single VID/PID combination (how many vendors need 64000 PIDs?), probably generating far more revenue for the USB organisation. [/rant off]