Yes - do it, definitely. I started shooting suppressed about 1 year ago and now have 8 suppressors. For your AR15 you won't NEED ear protection if you're shooting a few shots here and there (like hunting) but a day at the range shooting multiple shots will definitely require ear protection. There is NO completely hearing safe solution for an AR. Now a bolt action 223 yes, can easily shoot with no hearing protection but not an AR.
Second point I would make is there are so many good suppressors that one recommendation is just as good as the next. Just need to decide if you want to go direct thread or invest in a mounting system. Also as somebody mentioned, you can go to a 30 caliber suppressor and have that flexibility down the road there is no audible difference in loudness.
You don't need a huge can. Length is not completely irrelevant but certainly not a basis I would go on. VOLUME of the can is more important but again, 223/5.56 is a small cartridge so no need for a big can. My cans are all in the 7 to 8.5 inch range with mount for what it's worth all rated for .30 magnum cartridges. My cheapest can is a Silencerco Omega 300 DT which retails about $600 and I can't audibly tell a difference between that and my $1100 suppressors on volume.
Oh, one last thing - you will need a heavier buffer weight for your AR since there is more backpressure with a suppressor. It will work without the heavier buffer weight but you'll be beating up your rifle needlessly. I use H2 weight.
Also, the standard style suppressors tend to be gassy - get gas blowback on your face from the backpressure. Newer flowthrough designs are supposed to be better but I have no personal experience with the flowthrough designs but something to think about,.
Let us know what you end up getting.
