Subsonic .223 rounds are called 22lr.
Not in my book. A 1050 fps 40 grain 22lr bullet gives me 98 ft-lbs. The Aguilla SSS 60 grain at 770 fps (best velocity in my guns) is merely 79 ft-lbs and needs a faster twist then the typical 1-16 for good accuracy.
I loaded 70 grain speer bullets in my 1-9 twist suppressed ar-15 and got decent accuracy with a bit more noise than the suppressed subsonic 22lr. At 171 ft-lbs, it is far superior to the subsonic 22lr in any form as far as power is concerned.
If you need less noise, go with the suppressed subsonic 22lr, but never confuse it with the power that can be had with a heavier bullet.