Would 38A be a good backup for 38G since both are part of Civil Affairs?

I was able to sit down with a few 38G at my new unit. They mentioned that a 38A can be a 38G but a 38G cannot be a 38A. The recommended to go for 38A first, then switch over to 38G, that way if I want out, I can resort back to 38A. Something to consider, other 38A/G please correct me if I am wrong. So based on my knowledge and advice from a current 38G, go 38A first.

Keep in mind I am a 38B now. So if I went straight to 38G I would essentially corner myself into that niche - which is fine by me.