As current serving Combat Engineer I can say: Yes you can adjust real life army experience in here, does it always work? no. It's ARMA and ARMA likes to do it's own thing. Leadership and experience isn't always connected to real life service. Yes, it will be noticed, no it doesn't give any privileges for this Unit.
For me it was adjusting all my experience to ARMA, because you simply can not compare a online Milsim with real life but you can find a way how to use real life knowledge into this after a while. Even, learned different things, from this Unit from non-military members here that made my vision on things different. And there are plenty of good leaders and members here who got all the experience even they never served in the military.