HW is about as good as it gets for a general purpose off the shelf unit.
I tested the 4 of my 6 different Moderators i have last week when i got the adaptor to add a second one to my FN12.

The db numbers are not super scientifically measured but I did use the same meter in the same conditions at the same muzzle distance. It's a pretty good guideline.
Falcon QF - 98
Swift Stumpy - 94
ECS DeathWhisper - 90
HW - 88

Bear in mind that every 3 db is a doubling of power.
Remaining two are not directly comparable (Daystate Reflex & Falcon Male UNF)
From testing on my MK4 last year the HW does beat out the Reflex.

Only nice thing about the ECS is it's super light and matt finish.

Basically you cant go wrong with the HW - and if you don't like it they sell very well on here; always a good indicator!

Edit - I should point out these are for direct comparison only. The action on the FN12 accounts for the vast majority of the sound measured.