Scanners tend to be slow though, even on low quality you won't get the half second hand scan of hollywood.
Well that's when you break out "Everything isn't like it is on the movies!" I know that high DPI scans take time and will especially do so on old scanners.
I've heard fingerprint security just isn't quite there yet. It allows a lot of things even when it shouldn't (people have tested 'gummi bears' and it allowed them to bypass that).
Gummi bear tricks are akin to what happens to users logging onto Windows under an administrator account for normal-user use, as most often prints are lifted from
the scanner itself (WIPE OFF AFTER USE, GEE!). Obviously process failure will cause holes. It's like buying a 1000 dollar lock on a 15 dollar hollow wood door. To defeat the lock, kick the door in. And you can still probably 'pick' the lock anyway. All of that is even moot if they can just open a window and climb in instead.
AFAIK all the finger print readers available today can be tricked with ridiculously simple ingredients. http://www.ccc.de/biometrie/fingerabdruck_kopieren
I don't see how this is different than picking a simple pinned door lock or hacking a Windows pass remotely through some IPC exploit. Obviously professional biometric systems need enhancements (I have to believe the industry has since thought about things like temperature, electrical resistance, passing a magnetic field, etc. to prevent fake finger shenanigans. I mean, you should have to cut a guy's hand off...)
I envision my test for door access as opposed to computer security. Clearly just setting up a single biometric (and outdated instrument) is of questionable prudence, its most probable issue probably not that it is any less secure than a standard house lock but that if it is the sole access control that opens the door and only mains power is applied, a power disruption will lock someone out.
Because the lock on the door is only such a deterrent for those unwilling to brute force their way in, any key system should probably be paired with at least a camera, and in the case of an access control using electricity, a significant backup battery.
Moving from a single print to at least 4 fingers or even a combined palm (that's the joy of the fullsized scanner window) probably decreases the ability of someone doing preliminary stalking work for prints because not only will they have to collect all the individual parts, they will have to assemble them at the 'appropriate places' which they may not be familiar enough with, to reconstruct the hand.
There's of course always the question, can someone attack the interface by removing the part that images the hand and just pumps in a false image electronically (i.e. the 'hand' has already been 'scanned' elsewhere and some sort of electronic interception/deposition is occurring to pump in what the scanner thinks is an image it took.)
Just things to think about. Maybe the only difference between a print and a key is how you might lose one or the other and what the consequences are. Can a locksmith pick your scanner? What happens when you finger is damaged?