I think the 5*'s handle ice very well. Actually, that's one of the reasons I bought a pair...our local ski areas = alot of ice at times. I agree the 5* has a "bigger sweet spot" than the 6*. I had more fun on them when I demoed both and is the main reason why I bought them. You can push them real hard or just sit back and relax with them(they do like to be driven, but, it's not required). The only thing I think they are deficient in is powder. It handles powder OK, but, I would have looked for something else if more powder skiing was available for me. If you have to ski mostly groomed and/or icy conditions(western PA for example) than the 5* is a great fun ski. I'm about 5'11" and 210 lbs. I'm not sure what to tell you about the size difference you have over me. I've heard that individuals your size may enjoy the 6* more because they can flex the ski easier, but, I don't personally know anyone your size who skis, so, it's just hear-say for me. Hopefully, someone will chime in who is more your size and give their experiences on them. If you can demo them, do it. I'm glad I did because I was interested in the 6* before demoing both. Good luck!
I almost forgot...I agree with StormDay. The 6* does require more attention than an intermediate skier may be able to give. Likewise, it may even disappoint a more advanced skier who is looking for a ski that they can relax on when they want.