My 2¢ worth of opinion...
Irons Forward has one slight advantage in that the rear iron cannot obscure the dot in the window... Even with very low irons it is possible to hide the dot behind one of the ears with Irons Rear. As I said, it's a slight advantage.
That said, with an enclosed emmiter like the ACRO, Irons Forward will move that giant box of RDS further back on the slide and potentially make concealment more difficult.