Dude, your doing all this for one movie!!!
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Seriously for how often you would actually hit a 10Hz signal in most movies, I would stop worrying about and just enjoy the 4 subs you have. I think unless you go IB or the Thigpen yoru never going to achieve what you want even with four Ultras.
Although I would love to hear 4 Ultras in one room, that must be insane. I have the 10" subs in my BP7001's and my SVS NSD 12/2 and I think I have enough bass, I can't imagine what four Ultras must be like.