I agree with what Apocalypse has posted regarding ArmaA. To quote from the front page of the Dogs of War VU web site:
"We are a mature group of players who utilise military simulations in an immersive environment."
ArmA definitely is a military simulation and has tremendous potential for immersion. Like others who come to this VU I thrive on immersion. Steel Beasts is the core of this community, but we have branched out to other multiplayer sims: ArmA and DCS to name just two. It is my opinion the most attractive part of the VU is the consistency of scheduled events and the command and control (i.e., "you this is me, over") we employ during some of those events.
With Steel Beasts one need only master two things, really: Steel Beasts and Team Speak. Perhaps a third thing is mastering Zulu/GMT time conversion

With ArmA there is a learning curve as well. ArmA has an added challenge of mods and finding the appropriate mods to support immersion that are balanced with ease of use and consistency.
I am very confident we can achieve the level of immersion we enjoy, it just requires structure: a set day/time, and the C2 we already employ for Steel Beasts on Saturday missions.