Replying to Volkl Pearls

i'm looking to get a pair.
unfortunatley, they only go up in increments of 10cm.
so i'm stuck on whether to get 158's or 168s
right now i have 153 Line Celebrity Mini's, and i feel like if i go up to the 168 Pearls, it would be too much of a change, and i wouldn't be able to throw them around.
then again, i don't know if 5cm is ENOUGH of a change from the 153's i have now.
extra info:
i'm 5'6, interested in doing some backcountry this year, but will most likely still be stuck with mainly park/all mtn.
opinions?