18 sound change of CD in suggested design?

You would need frequency response data
Showing the driver with Horn.
Doesn't seem to be provided by 18 sound.

Otherwise using same software you could acquire data
with microphone and interface.
Rather long learning curve either way.
 
I have heard the HD1050. I can't say anything negative about it but since it was an open air concert, the tech guy got a lot more influence on the sound than the driver, that's not going to help.

From my experience though, you will not hear the difference between them if the crossover is adapted to the different driver. If you don't change the XO then the ferrite will definitely sound better.

I personally would save the money, the speaker is well developed and there's no gain in putting in the effort and time to develop a new crossover. Since I'm lazy too, I would not spend more money to have work to do to get to the same result. The only reason to do so is if the 500g difference in weight are absolutely critical.