I can't really help you specifically since I am using sptech av-2s, which are nowhere near the level of the minis, but I am having good luck crossing over right now with 2 subwoofers @ 60hz, one with phase reversed and the other with phase at 70degrees or so, placed near the midpoints of the side walls. This is the best balance I've had to date in my problematic room. One is a hsu vtf-2 and the other is a GR Research 12" w/ passive radiator subwoofer. Both the av-2 and mini have f3's of circa 40hz, but the av-2 rolls off more slowly than does the mini - however, there is no question that the mini design hits both harder and more cleanly, given adequate power. I find it doubtful that you will be crossing at 100hz or even 80hz. Without a doubt, good placement will have a large role.
My subwoofer system is not completely dialed in, but I am satisfied enough with the integration that I am going to just listen and see if I stay satisfied. So far, 1 week and still happy.