Some generalities on crossover filters when crossing over similar types of cabinets (front loaded subs and LF sections):
Generally 24dB/octave LR filters work well because they sum (power) nicely acousticly around the crossover point. The type of filter depicts the shape of the response around the knee. Butterworth is a sharper, steeper initial transition and works better for high pass filters on the subs. Phase response out of band is a little more friendly too.
Generally, the sub's high pass filter should be somewhere between the -3dB and -10dB response point on the sub, closer to the -3dB point if you plan on driving the snot out of your boxes.
Generally, 100Hz LPF is about right for most subs and tops, and if the subs are folded horns, or the tops are 10's/12's, lower than 100 Hz is probably not indicated. In this case, folded horns are most efficient between about 70Hz and 150Hz, so rolling off at the beginning of the highest efficiency area of the sub's response curve is like shooting yourself in the foot. If you have a bump in the response, use your 1/3 octave eq to bring it down a little. Generally the bump due to the room acoustics along with system efficiency occurs berween 100-125Hz, at least in the larget rooms I typically work.
Also, unless you really know what you are doing, keep your boxes powered to between the RMS and 1.5x the RMS speaker rating and be sure all limiters on amps are engaged.
Hope this helps.
