...when they opened that hatch, they didn't really sound like any of them.
The enclosure in front of the speaker will change its sound characteristics anyway. When you open the hatch it acts like a kind of horn, so there's lots of diffraction, big change in frequency balance and also sounds louder than the speaker would if mounted on a flat baffle.
With the hatch closed it will sound different again, and its mechanical and electrical responses will change. That's why if you stick e.g. a V30 in an iso-cab the sound is different from a V30 in a normal 1x12.
To get a V30 sound in an iso-cab you'd have to start with a speaker which doesn't resemble a V30 when used in a normal cab.
Perhaps Eminence have designed a speaker specifically intended for iso-cab use here? Someone ought to, 'cos the normally-desirable speaker specifications are not well-suited to being used in such an enclosure.
I checked these out at NAMM and was very impressed with the amount of sound reduction.
Note also when the hatch is closed the greater air pressure on the front of the speaker limits its excursion -- the cone is actually making less noise with the hatch closed than when its open, so not all of the reduction in level heard from the outside is due to the sound isolation. That's important to bear in mind if you need an iso-cab to keep external noises out -- don't assume if the speaker sound drops by say 40dB when you close the hatch that external noises will be reduced by 40dB inside the cab.
To get the normal sound of the speaker used in an iso-cab you'd have to modify the acoustic impedance, e.g. by loading it by using an air labyrinth. Rivera do that, but their iso-cab is hella expensive.
Iso-cabs have a distinctive quality to their sound, in greater or lesser degree. Some like it, some don't. And like normal speakers, they all sound a bit different. The advantages of acoustic isolation are IMO null and void if the resulting sound compares unfavourably, by your taste.
