There will definitely have to be some trading going on with the ROTC packs. Hasbro sent me a box of the Booster packs to review and out of 30 packs I was able to make Menasor and Dreadwing but only parts of the other 4 Combiners.

It will be really good to swap Combiner Characters down the road when people build up doubles. For instance I have 2 Mirages but need a Sunstreaker and Ironhide to make Optimus Maximus.