First, "slightly quieter at a given volume point on the amp" and " not able to go as loud" are two very different things.
Second, we are comparing a single BF One10 to a Ampeg 2x10.
So, I agree with Anton here, Alex's cabs DO cover a lot more if a single One10 is pretty equal to Ampeg's 2x10 volume "at the same settings" as is the case with Diaper Geni's comparison. "Slightly louder at the same volume point on the amp" means little... it does NOT necessarily mean the One10 can't go as loud as the Ampeg 2x10, it just means you will need your volume knob to be ever so slightly farther to the right to be there. ... if the Ampeg is slightly louder at a given setting, then turn the One10 up a little bit. Now, equal. Unless you run your amp at 100% volume normally, and no one does, I think it's a non-issue IMO.
Also, DG says in his comparison that the One10 is more even across all strings and all registers, and has more bottom end, than the Ampeg... yes, more bottom end on the One10 compared to a 2x10. Those two aspects are way more important to me that a slight volume difference "at a given volume setting on the amp".
To each their own of course, but...not sure why @sratas would take away from all this that the Ampeg is better and that Alex's cabs don't cover as much as he thought... unless sratas misunderstood and thought this was a comparison of the Amepeg with Barefaced's TWO10, which I don't think is the case. Now, of course, it's possible he'd prefer an Ampeg 2x10 to a BF One10 anyway, since people's opinions vary on everything/anything... but without hearing a One10, and hearing only Diaper Geni's comparison, I think it would be a mistake to arrive at that conclusion without personal experience.Just my 2 cents.
That said, there are natural limitations to any single 10" speaker no matter how awesome.
I know buying a BF cab takes, for most people, a leap of faith because you can't sit down and listen to one at your local Guitar Center. Just based on my personal experience, I'd say, don't dismiss the Barefaced and conclude something else is better/louder/whatever, until you've actually tried a Barefaced. I have heard of people who didn't seem to like the Barefaced as well as most do, so obviously there is individual variation... but I would not dismiss the BF and decide Ampeg is better having not heard the BF, or conclude the One10 won't go as loud as an Ampeg 2x10, because that is not what Diaper Geni said.