totally agree on this...I'm 5'11 bought 179 hellies and though they are great and all but I should have bought the 189s..just increases the surface underfoot when you're on piste and added flotation off piste..
Rockered skis should be bought 10cm longer than what you would normally buy for a regular cambered size ski for your height/weight.
The rockers ski like a 156 or 166 on the groomers... they have waaay less contact with the snow because of the rocker. For that reason, and that reason alone, means that you should rethink your ideas.
a 171 rocker would be like a junior/females ski. and most females I know would be happy on the rockers as they are. There is no real demand for it.
If youre 5'4 and weigh over 110 lbs, i'm sure you'll be just fine on the reno rockers as they are at this time. The End.