I did a 13 month tour with my brother, and I think I shaved 4 times - every three months or so. The beard didn't hurt our interactions with people - I think it almost helped, by giving a good conversation starter. After 3 months a beard gets really long. Plus it helps with pictures to be able to quickly identify how far into your tour you were, based on beard length.
I say go for it and don't look back.
Here's one of our shaves, in Peru:
