RE: Wanting to make the move to giant scale.
I personally wouldn't go with the traxxas as there is no aftermarket support for it, and getting replacement parts is hard since you have to go directly to traxxas. For whatever reason traxxas refuses to let hobby shops stock parts for their buggy. The problem with that is what happens if traxxas decides to stop making their buggy? Parts replacements will be next to impossible to get.
Whether you go with a FG or Duratraxx/Carson/XTM depends on what you plan on doing with the car. The FG cars have alot more aftermarket support especially in the alloy replacement parts. So if you are planning on buying a bunch of alloy parts for your car/truck then go with an FG. On the other hand if you go with a Duratraxx/Carson/XTM you can buy replacement parts for them straight from [link=http://www2.towerhobbies.com/cgi-bin/WTI0005p?&I=DTXD97**&P=Z]Tower Hobbies[/link] which are way cheaper than FG's replacement parts.