The MMGs aren't going to be able to fill such a volumous room very well. Also, I don't think the 7125 has enough grunt to get the job done with the 1.6's either. It might work, at lower levels, but these speakers get hungry for power. I'm pretty happy with the way the 755 drives the 1.6's, but that's almost twice the power of the 7125.
The 1.6 is a fine speaker. I love mine. If it was me (and it isn't), I'd just get something with a bit more power than the 7125 to drive them, especially with that high ceiling. You could always cart the 7125 down to wherever you auditioned the maggies and see if they'll let you swap it in for a listen. It might sound OK, but I know that with my higher level listening habits, it probably wouldn't be the best fit.
The 990 is a no brainer. I love the 990.
Hope that helped.
Cheers,
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