Effectiveness of status resistances?

so say I eat an HQ black drop (sleep resistance +5). Does this mean 5 seconds off? 5% off? does anyone know exactly how it works yet?

The status materia cost just as much as a peice of pvp gear (which will really suck if you want to try to multi-meld them), so is increasing status resistance in pvp worthwhile at all? The only ones that would seem to be useful in pvp itself would be stun and sleep and maybe heavy. Players don't inflict the Poison effect so that doesn't make sense.