I've been syncing for years with the USB cradle and USB HotSync cable that came with my C.
I had to replace the cable as it took a hit and the plastic at the Palm end shattered.
So far I've purchased two different USB/charge HotSync cables for the C from two different vendors and neither will work for a HotSync.
Though they both work to charge the C and Card Export works over both of them.
And, yes, I can unplug the new cable, plug in the old cable or the cradle, and HotSync still works fine with them.
The only difference I can find is that with the new cables I have to start the HotSync with the app on the Palm, instead of the hard button on the original cable and cradle. The HotSync app opens, it tries to sync, then errors out saying:
The connection between your handheld computer and the desktop could not be established. Please check your setup and try again.
Though I can connect the old cable or cradle and the HotSync app works fine.