Ummm---I didn't say that as a marketing tool. I don't know of the various HPF's available---only a couple. To me--they did what they were supposed to but the sound was compromised as well.
Now it's not a commercial product yet, but my eyes were opened by the HPF that Sonic Farm guru Zoran came up with.(on their new bass amp--which I am involved with). All of a sudden my 110 cab (with the hpf engaged) went as loud before fartout as my 112 (without a hpf) And the low end was punchier with much better impact. Makes sense--by removing the unwanted subsonics, your amp and speaker can do what they need to do.
Kinda why I asked. I've tried a few (and open to trying more) and there were more negatives than positives. I've been looking for one that I don't have to give up more than I gain.