Nearly everything I have seen shows that the game systems don't really see much improvement. In more cases than not you might see some slight improvements in level loads but in some cases the console's disk subsystem can't even handle the performance from good 7200rpm drives making SSD's a waste in most cases.
There is a reason why installing a game on a console takes longer than it would to "install" the same amount of data on PC. The consoles are generally geared towards graphics hardware leaving the general purpose CPU able to be slower and cheaper.