If they told you that, they honestly don't really know their shit. A 182 rockered twin is going to feel significantly shorter than a traditionally cambered twin. The 176 will feel like a 170, the 182 will likely have very close to the same effective edge as a traditional camber 176. Also, I'm 90% sure the turn radius on the 182 is shorter than 18.2m. More like 15m or 16m.
Also, the T-Hall is likely a poor alternative. These skis are not similar. For one, the Alpha one has a sintered base that will feel quite fast compared to the extruded base of the T-Hall. A closer alternative in traditional camber would be the Pipecleaner, which I highly recommend.
With that cleared up, I love both rockered and traditionally cambered park skis. I don't notice any difference in stability (I ride ON3P though and they run stiffer than average park skis), and I like having a stiff ski that is still easy to butter and take off switch.
If you have more doubts, call up SlopeStyle in Breckenridge and talk to Chris. He's ridden everything Armada has (since the company has existed) extensively and carries all these skis. He knows his shit and can point you in the right direction for sure. 970-547-4417