I am thinking about implementing HID in stead of USBxpress but the data rate to the device must be at least 96kbyte/s. Normally the maximum is 64. Is it possible in any way to use 2 endpoints for sending data from host to device? Can the control endpoint be 'abused' for that?

Edit: second solution gives you guaranteed bandwidth.

a) The transfer speed is altered depending on the host controller on the PC.
OHCI can transfer multiple stages of control transfer in a single USB frame, but UHCI takes at least a single USB frame for each stage of control transfer. That is, it takes at least three USB frame, for setup/data/status, on UHCI.

b) Control transfer handling puts considerable load to the firmware than communication over other endpoints.

2) Two HID OUT EPs
As Patryk pointed out, a composite device, HID + HID, is required to equip two OUT EPs on a single device.

Please note, the arrival order on the two OUT EPs on the device side may be reversed from the order you sent them on the application. For example, the application sends packets to EP2 and then EP1. But the device may receive EP1 first, and then EP2. If the order is important for your application, you must assign a byte on the data to show the packet number to sort them on the device side.

Anyway, it is unfortunate that there is no bulit-in class driver that supports bulk transfer with the flexibility like HID. CDC supports bulk transfer, but it is tied to virtual COM port on the PC side.

UMDF seems promising, but it is still under beta yet, and supported only on WinXP and Vista. ("USb diver in windows VISTA")

Tsuneo