Help needed choosing a 15" for 2-way

I'm close to move into new house, new possibilities will open.
i'll even have "semi-anechoic 2pi space" made of old underground water tank of 10m3. I'll certainly do measurement of those 15ntlw there. I am also interested why AE doesn't post any imp/FR graphs. not mentioning Klippel result or measurement like Purifi does. some coincidence?
In my customer support mail to 18sound they admitted that all Resp graphs will be updated with 260l closed box measurements. a side note- You can deduct something about their motor quality reading through Voice Coil test of differential drives in their 18" and 8" woofers.
There are tow minuses to those 15ntlw for OpenBaffle:
1. it is their 8mm xmax. even though they can do low dist above that, it's still too little air moved for party@home. i'm having 4ohm versions, this disables option to gain +3dB after series connection like 8ohm and I don't want my hypexes down into 2ohm.
2. You have to use hipass from 30hz up due to huge voice coil move there, Vituix shows only few speakers which control subsonic excursions well.
 
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