I don't have the XC tour I just bought a 2011 XC. I don't think there is any necessity for "cams, power commanders, etc". It mostly just a personal preference about how someone wants a bike to perform. I suspect for the vast majority of XC owners they run just fine in stock form. Since you are coming off of a Road Star I suspect the performance of the XC will probably be pretty similar. I myself came off of a Raider with a larger 113" V-twin that made gobs of torque so I'd like the 106" in the XC to have a little more punch that I'm used to but it is by no means necessary.
As far as being sold a bill of goods by the salesman I don't know that you really need to worry about that. There isn't much they can sell you except maybe an extended warranty that you probably don't need. I don't think the Polaris dealers are like Harley dealers in which they try to sell you a bunch of accessories and clothes when you buy the bike. Other than that you just need to ride the bike and fall in love with it!
2011 Cross Country
-Cee Baileys Windshield & Lowers. Victory Lower Bag Rails, Driver And Passenger Backrests.
-RPW Exhaust, Lloydz Air Filter, VM1 Cams, ATS (Timing Wheel), 1/4 turn throttle & IAV. PCV with Custom Tune by Coweta Customs.
105.2 HP & 127 Ft-Lbs on a Dynostar (Eddy Current) Dyno.