Certainly the Redfly is limited by the hardware it is hooked up to. And Im not sayng that everyone will get the same results I did.
However so far with the Redfly and the HTC Advantage (Advantage using a beta driver, Avantage not officially supported by Celio), I've gotten the following which I could not get with the usb out on the Advantage 3in1 cable usb solution alone:
2 keyboards
2 mice
1 hard drive
Cf and sd card on Dell Axim x51v running card export
However the Redfly seems to interfere with blue input program (formerly bluemouse). Also using the Redfly usb, I was able to read cf cards on the multicard readers with about the same frequency as with the Advantage 3in1 solution (one worked, two did not) . I also understand that some people got usb mice working on the advantage using 3rd party xda developer drivers, all my tests were without 3rd party drivers.
Conclusion: while the affectiveness of Celio's usb solution likely varies widely from device to device, and is certainly not as good as xp in any case, I was and am impressed.
Same device, 2 different usb solutions, a MUCH better usb experience with the Redfly.