I don't have much to add over and above what others have already mentioned.
I'm guessing that most or all A-list clubs have built their reputation using a reasonably specific musical format. Whether it's rock, country, dance, electronic, heavy metal, whatever......their customers go there expecting a certain type of music. And being pretty well established, they're probably not going to vary too far from that format.
And sad to say, there probably aren't many club formats where an acoustic-oriented pop/rock/dance trio would fit the bill. (Unless they have "Acoustic Wednesdays", or something like that...in which case OH would probably be perfect).
Most A-list clubs try to promote a loud, energetic atmosphere. Unfortunately, when people hear the phrase "acoustic-oriented", the words "loud" and "energetic" probably don't apply. I wouldn't call it a stigma, per se....it's more of an apples-and-oranges kind of thing.
There's no question that OH could be very successful and stay very busy with your current format.....and it's a great format.
But at the same time, there are a number of clubs where that format may not be a good fit.....and if you're looking to get a foot in the door at those clubs, you'll need to adapt your format to something a bit more in line with what they typically offer.
(This is not to say that you'll always have to conform to their standards. Once you've established yourself at a club, you could starting mixing in elements of both formats....like maybe doing your entire first set on acoustics, or whatever.)