The FFF's and Pow's are completely different skis. You'll need to determine what you are looking for in a powder ski.
For instance, the FFF's have a flex specified by Lib Tech to be a "6" at the 185cm length, while the Pow's have a flex of "7.5" at the 191cm length. Do you want a softer pow ski, or something stiffer that will be more supportive for your size?
Also, take into consideration both the length of the skis and the sidecut (turning radius.) The FFF's have a 16.5 meter sidecut at the 185cm length, while the Pow's have an 18 meter sidecut at the 191cm length. Essentially this means the FFF's will want to turn more than the Pow's; combined with the shorter length, they won't offer as much stability as the Pow's will for someone your height/size.
This isn't to say either ski won't work for you, but should give you something to thing about during your decision making.
Here is a review on TGR of the new FFF's for your reference;
I've owned a few pairs of Lib skis in the past and really would like to try out the FFF's, I just wish they offered a 191cm or so length and a slightly stiffer flex, but that's just me.