Jake
I have experience in this area so here goes....
I can tell you that galvanizing does protect the steel underneath from corrosion. The only thing to interrupt this protection would be some type of mechanical abrasion stripping the coating, once one spot is bare rust tends to travel depending on the position and location of the blemish. Also it is important to have the galvanizing done by a reputable shop, there are several steps in the process such as acid dip, flux dip, etc. to inprove adhesion. The only drawbacks To galvanizing are that is is difficult to make paint stick, and areas such as tubular sections of the chassis need to be vented before being dipped. This is because the hot zinc is at about 850 deg.F or hotter, and there is a chance that closed tube sections of a chassis for example can actually blow out. I tried once to have a set of railings galvanized and sent them without any venting holes...well they came back galvanized but with ugly holes in the horizontal and vertical components cut by a torch, so if you are doing a chassis it has to be vented if it has any closed sections. Otherwise it is great protection if you don't mind the color
Regards
Phil