You might ask Greg
at the California Ski Company in Berkeley. He was a great booster of last year's Xenons. Greg's blog
has some interesting info about Sierra skiing and the ski biz. He has some very complementary things to say about bootfitting instruction from Epic's SierraJim.
I ski last year's Xenon 7.0 Those skis are FUN! I prefer my SuperShapes for higher performance and also better grip on hard pack, but otherwise the Xenon-7 is my everyday favorite. I don't know what they changed in the 8.0, but Greg probably does. He might also offer a good price on a pair shipped to you--worth asking.
By the way, I'm not a lightweight...I'm 6', 200#, very good medium energy skier, and I'm very pleased with the Xenon-7 170cm.