Haha, the controversy over GMAW/FCAW... I am a firm believer that MIG (actually MAG) is the best choice, but... Ma Mopar herself prefers FCAW over GMAW in the collision repair manuals it produces!
Technically, FCAW produces better penetration and a smaller heat effect zone. My experience is you need a lot of practice to FCAW effectively, oh yeah, and don't forget to reverse the polarity on your MIG to weld with any success with Flux core... Ground should be Pos(+) and the gun should be Neg(-).
And BTW, you cannot use bonding adhesives for structure in any vehicle, only in certain areas on certain cosmetic panels (roof skins/quarter panels etc.) The adhesive has greater strength in a lap shear application than welding, but has poor peel strength when compared to welding...