Do you have more than one ski? Is this your park specific ski? Is this your everyday ski? Anybody going to say anything other than t-hall=park and ar5=allmountain?
I have had both. They're from the same mold. They're the same ski other than the T-hall has a milled core which makes it a bit lighter and softer. Nobody keeps their park skis sharp so the detuned edge is a non-issue.
Also your looking at the 170 which leads me to beleive you're a smaller chap uner 150lbs am I right. Get the Tanner's it's only fatties who really need the stiffer core of the Ar5. Shit, I weigh 200 and I preferred my 176 t-halls to my 180 Ar5s in the park.