The Specwar is the quieter than the Harvester and SDN6.
The Harvester was developed to be a lightweight hunting suppressor used on bolt action or single shot rifle and the max rate of fire is 10 round per minute. If you go over this you need to wait for the suppressor to cool.
For your intended use I would suggest the Specwar. It is rated for calibers up to .300RUM and is also rated for SBR and full-auto use.
Specwar also comes with the muzzle device for quick attach/detach but solid lock up.
This. The harvester would not meet up to your needs. SpecWar is solid as it comes, no one hand on/off but has a great lock up system as seen by silencerco going back to in on the omega.