Your goals/needs are rather modest. This is why you can likely find a low cost driver to achieve what you are after.
Also your two examples (driver from - I believe it is - the manufacturers GRS and Morel) are not equivalent in terms of performance and represent extremes in cost. GRS is a low cost no-frills supplier. Morel is a boutique brand. Very different in terms of what the market will bear as well as their ultimate potential. It's a like comparing a Skoda versus an Audi when all you need to do is drive a short distance through town to the supermarket to buy a few items. Either one will perform the same as the other.
A car is a complete system, while a loudspeaker driver is not. I don't think your example is a very good one either, as I personally would prefer Skoda over Audi... at least within the same segment.
Let's consider this - an Eminence NSW6021-6 21" Tour Grade Speaker costs 1300$. That amount of money would buy you seven Eminence 15" Standard Series drivers. Which combination do you think will perform best, if we decide to ignore the fact that the 21" will require a much smaller cabinet....?
Let's consider this - an Eminence NSW6021-6 21" Tour Grade Speaker costs 1300$. That amount of money would buy you seven Eminence 15" Standard Series drivers. Which combination do you think will perform best, if we decide to ignore the fact that the 21" will require a much smaller cabinet....?
The Morel cone drivers are not designed very well. The magnet system they use generates alot of odd order HD in the lower end and ruins the performance pretty badly. They're ok as dedicated mids though, but just horrible in the low end.
Even though not very expensive, Eminence do have control over their production. Here's a near-field measurement of eight Delta 12A's from two different production batches. Any difference may just as well be related to my measurement setup, as the drivers themselves. The drivers were laying on a table with the mic 20 cm above. I might have placed them slightly different between each measurement. Anyhow - they show very good consistency.
There's no excuse to not have good driver to driver consistency in this day and age or mass production. I've gotten some pretty sloppy stuff from eminence in the distant past, but I think they have their act together nowadays. I do see the occasional shift in VC lead ins not lining up with the terminals on the basket and skewed / crooked cone relative to the spider and basket. I expect accuracy in assembly for the money they now charge after their huge price hike recently.
I have combined 8 low cost 6.5in woofers in a slot loaded open baffle (SLOB) setup and it provides some very nice bass and the mid bass has fantastic chest punch power and clarity. Super power handling of 500w and high efficiency (93dB). This is the bass driver system for my 3 way dipole and putting the magnet inside one side of the SLOB provides nice distortion reduction. About -55dB distortion and bandwidth up to 470Hz. Some of the best sounding midbass I have heard for $110 worth of drivers having same cone area as two 12in woofers.
https://www.diyaudio.com/community/threads/the-xsd-speaker.385717/
Distortion:
https://www.diyaudio.com/community/threads/the-xsd-speaker.385717/
Distortion: