I think a kit is the way to go, if you take the time to put it together right, you will know exactly how everything goes together and will make future wrenching much simpler. I am planning on adding a Savage SS to my rc garage in the near future. The things that are included on the .25 are things I am not interested in anyway.
Here are a few questions only you can answer.
Do you want to build it or just take it out of the box, add fuel and break it in?
Do you want the roto start or pull start?
Do you want a aluminum tuned pipe, or a composite pipe?
Do you want hd upgraded dog bones, or stock?
Do you want a prepainted body, or do you want to paint your own?
These are basically the difference between the SS and the RTR 25, answer these questions and you will know which truck to get.