I'm a new 436 & digital scanner owner. To be safe, I have always used the Windows "Eject" feature with any USB device. However, can the USB cable be pulled at any time, when the 436 is in "Serial" mode (as opposed to "Mass Storage" mode)?
For the 436HP (or, for that matter, any of the other 'database' scanners, such as the 536HP, SDS100, and SDS200), there is no problem simply disconnecting the USB cable as long as the scanner is in Serial mode. Using "Eject" is not needed.
There's one caution to that, though:
If you are powering the 436HP via the USB cable, either because there are no batteries installed, or the batteries in the scanner are too discharged to operate the scanner, then you would need to turn the scanner off before pulling the cable. You would not also need to use 'Eject'; just turn the scanner off (again, that is needed only when operating with either no batteries, or the batteries are too weak to run the scanner).