The FRS/GMRS radios have two license groups. If you are using a radio with both, the FRS channels will operate on a lower wattage transmit than the GMRS. Ski Patrols are widely adopting the 9-11 as a standard. It is in the GMRS, which means higher output. (Also, FRS use by business, public safety or government is prohibited by the FCC)
Reception, on the other hand will not change from one group to the other.
Both groups are UHF which is notoriously affected by terrain. The signal does not bend like HF or VHF signals. You can't get the advertised 5 mile range if even a modest hill is between you.
Another thing to consider - When you are on a selected carrier channel, say "7", any other traffic on 7 will impede your ability to transmit or recieve, even if they are on a seperate sub-code. The sub code is constant tone coded squelch, which is simply a "squelch toggle", not a seperate channel.
As such, avoid using channel 9 at ski areas, even with a different sub-code.