I ordered 3x Boston A26 as my left, center and right and would like to comment on my (somewhat positive) impressions. Hopefully, this will help people like me, who didn't get to listen to them locally before buying.
I hooked up a signal generator, but used my ears to judge relative perceived sound levels.
1. The speaker response is very flat. Sweeping through all audible frequencies, there are just a couple very minor resonances in the low mids. Across the cross-over and tweeter frequencies I cannot spot any resonance with my ears.
2. The bass starts to slowly decrease at about 70Hz to I assume half power at the 52Hz from the datasheet. Fortunately, further down the roll off isn't steep at all. The speakers are audible all the way down to 35Hz.. Curiously, there's a peak at 25Hz where you can actually hear it. Nothing at 30 though :/
3. Physically, they are much deeper than it appears on the pictures.
4. Qualitatively, sound clarity is good. While playing acoustic music, every instrument is clear and distinct.
5. Sound dispersion is very wide.
Now the not-so-good:
6. Bass is colored. Makes a double bass (contrabass) sound as if it has nylon strings. Boston claims good things with their polymer woofer, but to me it makes the sound more plastic.
7. The bass port is too narrow and generates audible noise.
8. Music just doesn't come out dramatic. Comparing to my previous (and admittedly 3x the size) speakers, the feeling of a real musician behind the speaker is lost.
When I first hooked them up, I had an interesting experience - I ran the Audyssey MultiEq and upon completing the wizzard it was disabled. When I reran the calibration - same thing. I went to the menu and after verifying the correct speaker distance I manually enabled it and I understood why it did not get enabled in the first place. It made almost no difference. Change was for the worse - the sound became more robotic with it. So there you go - you don't need Audyssey with these speakers if position well. (mine are on stands, 1 foot away from any wall).
System 1: Yamaha RX-V2500 + 4x Bose 501 Series IV
System 2: Marantz NR1402 + 3x Boston Acoustics CS26 Gen. 1
System 3: 3x JBL LSR305 + JBL LSR310s