as mentioned the suppressor would be very cool IMO. oh, do i wish that the powers that be didn't think my wishing for suppressors on our ump's as unnecessary.
in my experience using the electronic ear muffs (providing you remember/have time, batteries not dead,etc.) are better than nothing (i don't agree w/ simple disdain of potential hearing loss).
as i recall in BHD, Mark Bowden quotes Paul Howe as mentioning that he popped out his ear plug at one point so as to better hear talking that was approaching him-turned out to be somalies who apparently didn't realize how loud they were, as they were chattering away. if Howe wears ear plugs in combat, and he's about got the ultimate and deserved BTDT/ got the t-shirt reputation. i try to pay attention to actual experience.
the problem that i have experienced w/ the electronic ear muffs (qualification range uses the full ear muff, i can't remember the brand but the microphone faces the rear only. on the part time tactical team that i've been a member for 6 years, we use those tactical ear things-they look like old fashioned hearing aids- for one ear, radio plug in the other ear), the point i'm getting to is that you hear quite well behind you, but even normal conversations are hard to hear in front of you.
and for us, we're going towards the threat as we clear an area, even though you're going to face a similar problem as you are barricaded and waiting for the calvary.
my $.02.