As far as shooting any .223 weapon in close quarters you will definitely need hearing protection! Try Peltor’s Com-Tac (around $250ish I think) or Aearo Combat Arms Earplugs ($7 a set). Both are a lot cheaper and have A LOT less paper work to acquire than a suppressor. Yes, an attached suppressor will not require the amount of time hearing protection will take to put on or in, but if the bad guy fires and doesn’t use a suppressor it is still going to be loud. I use the Aearo’s on entries or if I have time prior to deploying my AR. I always keep a set in the handle with the weapon. We train with one guy kneeling and one guy standing over him firing bursts from 11.5" barrel Bushies. It will definitely get your attention! But you can work through it when you know what to expect. If you’re forced to engage a suspect, burglar, etc. at any time you should have a quality light (Surefire) on your weapon or at least one with you. If the light is activated (for target ID) then the flash from the barrel, even with out a F/S, will be insignificant, but the Phantom and the Vortex both due a far better job than the A2. Now as far as Barrel length for .223, my understanding is that anything under 9” will not give reliable penetration of soft body armor. So if you are not worried about body armor then a shorter pistol caliber weapon will be far better on the ears, etc., but then comes in the question of pistol caliber rounds over penetrating the bad guy, interior walls…
Ray