While most PS3 owners will be tempted to install Devil May Cry 4 to their hard drive, it's worth asking if there's much of a benefit. Why? The full 5GB install will take over 20 minutes. But the load times really aren't much faster than playing off of the disc, only gaining about a second in most situations over the 360 disc version.
However, without PS3 to PS3 comparisons we may be discounting the possibility that the Xbox 360 version has better disc load times than the PS3 version, so there could still be a considerable loading benefit for PS3 owners. Even for 2 second savings, I'd leave the game installing while I did something else.