I came at it sort of backward...
Went through Infantry OSUT as a Reservist, then went active as a Signal Corp guy (36C, 31L, 31V...) Became an Echo and had a fairly easy time with a majority of the MOS-specific stuff since I had done a lot of it already (including a lot of the antenna theory...etc). I was very happy to have the 11B background (as limited as that exposure was) when it came down to it in the course because it is one thing to fumble around a bit stringing an antenna...it is quite another to walk around for hours and make poor tactical decisions(dragging your team behind you) because your basic infanty skills suck.
Unfortunately for you it is impossible and impractical to be strong in one area and weak in the other...
Do both and do them well...there are a lot of roads that lead in that direction. My personal thought is that if you are going to get into a signal MOS I would look for something with a more tactical spin to it. As a Unit-Level comm guy I worked with Engineer, Armor and Scout units so you are at least around a tactical mindset.