It has made quite a lot of space in my PSP Phat collection. In each Driveless mod I do I usually put a Memory stick storage spring into, That way you can switch from Memory Stick A to B easier than getting out some kind of case or your wallet all the time to swap them. The Drive is almost big enough for a 9 volt battery, Try taking one apart and making a Flat 9 Volt, it may help you make the PSP last 2-3 hours more, but you must put in a switch and wire that to the charging circuit.
NEVER CHARGE THE PSP WHILE THE 9V SWITCH IS ACTIVE!!!!
That way you won't have leaky leaky in the PSP.
Remember, Battery and charging mods are liable to Frying the Backlight Fuse in the PSP. Be careful about it.
If you fry that, you have to bridge the fuse with a drop of solder. from then on you can not remove your screen once it is installed or else it's backlight will be killed upon removal.