Replying to Rocker Length

Some of you may have read my thread from earlier in the week (A-Bangs vs. Rockers).  I have decided to settle on the Rockers.  But now the question is, what length should I get?  They come in 171 cm and 181 cm.  I am about 5'9" - 5'10" (175-178 cm), so I thought it would make sense to get them at 171, but someone said that due to the rocker and subsequent shortened running length, I should get the 181.  I will be using these for park, playing around, and the occasional pow day.  I am a bit wary of buying a ski that is taller than I am.  Here are my concerns:

-The skis will be too long for me to butter; I will not be able to get my body weight up over the tips.

-The increased length will make the skis unwieldly and hard to handle, especially in the air.

-I will not be heavy enough (roughly 143 lbs) to flex this ski properly, so they will lose their playfulness.
*the playfulness of these skis is a huge concern for me.  My Chronics are not playful at all, so I'm looking for a big departure from that.

However, if 171 is too short and keeps me from using these skis to their full potential, then I suppose I'll have to go up.  What should I do?