Let me check if I got this right - are you saying that all non-horn-loaded dome tweeter designs are suboptimal as avoiding to horn load the dome tweeter would increase low-treble distortion?
Haha, I wouldn't put it so categorically. But yeh, what I'm saying is somewhat controversial. Please let me explain my point in detail.
Direct-radiating dome tweeters perform well at low to moderate SPLs, and are excellent in terms of value for money and/or where wide dispersion in the low to mid treble is desired.
However, they always perform poorly in the low-treble if pushed to moderate or high SPLs and not crossed over relatively high. Although different dome tweeters perform differently, ultimately there's no avoiding this. Importantly, the performance of the dome at moderate-high levels will be most compromised in the ear's most sensitive frequency range (1.5-5KHz).
This means that direct-radiating domes make sense only when crossed over relatively high and/or not asked to play too loud, such as when matched to a smaller midrange driver or midwoofer. So they make sense in smaller two-way speakers or in three-way speakers.
In this case, however, we have an 8" woofer and 1" direct-radiating dome (I think... I can't find a close-up picture, but if there is a small, shallow waveguide, it is very small and shallow). It's my opinion is that the use of a direct-radiating dome is a suboptimal design choice in such a case.
There are two problems here as I see it, and only one or the other can be solved.
On one hand, if we want the dome to play to the same SPLs that the woofer is capable of, without heavy distortion or risk of damage, it will need to be crossed over quite high. This will result in very narrow lateral dispersion at the top of the woofer's passband (larger woofers begin to beam at lower frequencies), and very wide lateral dispersion at the bottom of the tweeter's passband. (Also, since the acoustic centre of the 8" woofer is quite a long way from that of the tweeter, the result will be a pretty erratic vertical polar response around the crossover point.) In most rooms, such a mismatch will be a recipe for brightness/hardness.
On the other hand, if we want to try to get a closer match between the lateral dispersion of the woofer and tweeter at the crossover point, we'll have to cross over so low that the dome will be working too hard at even moderate SPLs.
I'm sure that the designers will have gone for the former option, since the latter option would put the tweeter at risk of damage under normal use. But I'd prefer neither option. Instead, I'd choose to horn-load the dome, which would reduce both the level of distortion
and the lateral dispersion at the bottom of the dome's passband. This would allow it to be crossed to the woofer lower and/or play louder. It would also help match the two drivers' lateral dispersion at the crossover point.
Of course, while I believe my arguments are persuasive and supported by theory and evidence, this is still just my opinion. There are many other factors to consider in designing a speaker, and an 8" 2-way with a direct-radiating dome can certainly be made to perform quite well and sound quite good.