Does Time alignment and Phase coherency make for a better loudspeaker?

I've owned Dunlavy SC-IIIs for about 3 years now and a key feature of their design is time/phase coherency.

I've tried a number of different speakers over the past 3 years but keep coming back to the Dunlavys. Whether or not it's the time/phase feature of their design that appeals to me over everything else, I cannot say.

Speakers which have come and gone in the last 3 years include Quad ESL57s, Merlin Music VSM BME, Sonus Faber Cremona Auditor M, Dali Mentor 6, Klipsch Heresy, Klipsch Khorns, Tyler Acoustic D2, and I'm sure a couple of others that escape me right now.

I just sold the Klipshorns this weekend and the Dunlavys are back in their rightful place.

I think my next adventure will be to try a set of the PureAudioProject speakers with a horn driver. Anyone have any thoughts on the PAP?

I think the new Grandinote Mach speakers are the best speakers on the market 

Ahh, John Dunlavy. What an amazing speaker designer. RIP.  loved selling his SC IV's and V's back in the day. One of the best loudspeakers I've ever heard.

I have a pair of Thiel CS6 speakers for which time and phase coherence were prime design considerations. This was Jim Thiel's raison d' etre. The CS6 even had the tweeter in the center of the midrange cone to maximize the coherence of the speaker.

As for sound, I went to the 2018 AXPONA and was pleasantly surprised that my speakers and system holds up to pretty much anything I heard that cost less than 6 figures. I think my speakers sound very good for a variety of design reasons but the time and phase coherence have a significant effect.

As mentioned in previous posts there is a tradeoff for any design philosophy and in the case of Thiel speakers it was the need for high current amplification. My speakers have low sensitivity combined with a brutal impedance curve. I run them with a Krell KSA 300S amp that will put out 2400 watts @ 1 ohm and weighs 185 lbs. If you like tube amps you are pretty much SOL.

I've heard lots of good sounding speakers that didn't have time and phase coherency as a primary design goal but I think this characteristic improves imaging to some degree. The imaging in my system is almost scary. On some recordings I feel like I can reach out and touch the singer or particular instruments and the depth of the image is holographic.

Every speaker manufacturer has their "thing" that defines their unique selling proposition. For Thiel (and Vandersteen) time and phase coherency is their marketing hook but in both cases their designers combined a range of good practices to make their speakers sound great.

I agree with 8th-note.  I have the Thiel CS6 speakers too.   On some recordings I feel like I could get the singer's autograph.  The top Vandersteens are the only other speaker I have heard that does that and sounds a bit better.  All it takes is money.