I own a set of the Howard Leight Impact. They are not bad value for the price and better than the low-end Peltor Tac 6 but they are nowhere near the best.
I use Peltor ComTac for shotgunning and the Peltor ProTac for rifle shooting and indoor handgun. Compared to the Leights the Peltors have a faster response time, sound much better and are more durable. These qualities among other features make the Peltors worth the extra cost.
The Leights meanwhile are used as loaners when I take guests to the club.