I shoot Sporting Clays on a course fairly regularly. Though I use an auto loader. But 2 chokes is definately beneficial at some target stations. Normally you shoot the bottom barrel first and therefore want the more open tube there; like you have. But, for most SC target presentations full choke is not needed. I shoot an IC in my Gold and never change it. Though there is one station in particular at the course I shoot at where I should have a full choke...and full-full would be good on an o/u. You are shooting crossers WAY out...maybe 40 yards. They are actually angling slightly toward you so they get closer on the second shot...but you gotta lead those mothers big time.
But most targets are much closer than that...more like 20 yards, and some inside the 10 yard range. Full will make a nice poof of powder out of them though...your better off being more open. It might depend on the course you are shooting more than anything.
I think a good choice for the first time on the course is a IC, mod combo...and change one to a full only if needed. if buying more chokes you can look at custom extended tubes which make changing them out on-course a lot easier. My dad uses Seminole chokes in his Citori...you get your basics plus things like Skeet, Light-Mod, Improved-Mod, Light full, extra full...etc.
Its a great game...shoot and enjoy!