Any small speakers equal in sound to Hales Rev III

I think you'll find speakers like PSB Stratus Silvers or better NHT 2.9's to be much similar performing to the Hales Rev III's, and maybe a bit better!?
If you want to move up in refinment and resolution, you could go to small Thiel 1.5's used (800-$1200/pr used) if you want to stay in the $2100 new price range (but used obviously..yes?). How big is your room, and what kind of music however? You may require something that's more "BALLSY", so it depends.
I think, all around, you would do better with NHT 2.9's used. They'll even step up your sound a bit, and downsize your speaker size in the process! They do rock to classical great at that price range.

I went from Rev 3s to B&W Nautilus 805.
Yep. the bookshelf speaker.
Now, OBVIOUSLY, the bass response is nowhere NEAR the Rev3.
That is its greatest strength. I could never get them to image just right. I think the dispersion rings might be hurting the tweeter performance.

Anyway, I was very surprised to hear the same overall character to the sound from 50hz on up. Plus the Nautilus speakers all have killer imaging, increased resolution, and are just superb at throwing a 3d soundstage.

So, as far as an identical top to bottom speaker, I have no suggestion, but at $2k new, the B&W 805 is a great speaker, but weaker in the bass.

good luck

I would look at the new ProAcs or the SC1's. All would be a step up from the Hales and smaller in physical size. I have not heard the new Dynaudio 42 series, but that too may be a consideration. The new Meadowlard Swallow is more musical than the Hale, but not as detailed. You will have to make some choices here.