Hi Simon,
The 'chocolate chips' were worn in Gulf War 1 and Somalia(1993). The three-color DCUs were used first in Somalia and then through Iraq and Afghanistan. The digital ACUs started to replace the DCUs in April 2005, with the whole Army having them by the end of 2007. Units deploying overseas were given priority, so if your model's setting is 2006, most likely they'd be wearing ACUs. Additionally, Soldiers deploying to Afghanistan since the end of last year have been issued the OCP(Multicam) uniform.
I was in Iraq 2004-05, and we were issued DCUs, but our body armor was Woodland BDU pattern. The units that replaced us at the beginning of 2005 had all DCU stuff. I'm in Afghanistan right now, most everyone here is in Multicams, but there's still a few of us in ACUs. ( I missed being issued Multicams by 2 weeks). You still see a mixture of Multicam body armor with, say, an ACU radio or grenade pouch (or vice-versa).
Hope that helps,
Chris