I recently made a similar switch from 155cm Troublemakers to a larger ski. I'm only 5'7" and 130, and I'm riding 170cm Rossi S3's. I picked them up last year, and prior to picking the new ones up, I could spin 360 on the Troublemakers. They were mounted like 5 back from center. I mounted the S3's 1cm back from center, and I noticed the difference in the smoothness of spinning since the first day. I've gone from 360 to 1080 in 18 days of skiing these new ones. Prior to that, I was stuck with only spinning up to 3 for like two years straight. The spinning seems to be much smoother, and the stability that I've gained on landings is worh the extra ski to carry around. In my opinion, I'd say the new ones are the perfect size for you. 155'S are up to my chin, so I'd assume you're the same height, and you couldn't weigh any less than me, haha. They may take some getting used to, but mount them near or at center, and you'll grow to appreciate your proper decision. That's my $.03.
My tall tee has more stretch marks than Octomom. That's how G I am.