ok if you download down to 3.03 e c you will not lose any compatablilty because the popsloader plugin will still work.
-there are only 2 extreamly small things you will lose.
-you will lose the conserve memory option under internet browser (rarely even needed anyway)
-your dynamic normalizer function under music options (i dont even know what it does)
-but you will gain the abillity to fully customize your xmb.
i downgraded back to 3.03 oe c and i highly recomend it.