Single way or multiway

I'm not familiar with your specific listening standards, but to avoid harshness in the high frequencies, I found it necessary to remove the whizzer cone. The whizzer tends to exaggerate the treble, especially when paired with certain tweeters.

In this setup, I integrated a Fostex tweeter for better high-frequency performance. Using an RTA program with measurement microphone, I confirmed that the whizzer cone was introducing too much energy in the upper range, which negatively affected the tonal balance. Removing it resulted in a much smoother response.

@bache We're on the same page with whizzer cones! They are far more likely to have breakups of their own. I tried to find a version of the driver that didn't have one but as you know, to no avail. I don't play those speakers very loud and my crossover rolls the highs out of the Tangband (to help keep a nice impedance curve) but I've not had the guts to go after the whizzer. How do you do it? That strikes me as very easy to make a mess of it! 

In contrast, some other well-known and equally respected speaker companies — such as Voxativ, Zu, Cube Audio, and Totem — use crossoverless designs.

Who is right, and who is wrong?

@bache There are two issues: Doppler Effect distortion and beaminess.

The former contributes to congestion at high volume. The only real solution is to remove bass excursion from the driver. 

The latter causes the highs to be hard to hear unless you have your head placed in a vise. 

So a crossover is needed to solve both problems. 

IOW there's no such thing as a 'full range driver'. There are however 'extended range midrange drivers' such as the ones you listed. If you treat them as such you will have much greater success with their use. If you don't use a crossover, they really will only work at low volumes. 

I have a pair of Tangband 8" drivers in a sealed box crossed over to a matching Fostex tweeter. They are driven by a 5 Watt amp. I use them as monitors in my electronic music lab. They work great for that since I only use them at low volume.