I will start by answering Socketman. The amount of capacitance should be a balance decided by the amp designer. At some point increasing the capacitance further will mean you should also be increasing the continuous power output of the amp modules and the power supply that go with that increased capacitance. The flip side is reducing the capacitance; this can be an easy way to save a lot of money in the cost of the amp without reducing your continuous RMS power specification; this has the appearance of more watts for the dollar.
Matt is entering the area of multiple amp power management to get the biggest bang for the buck. The impedance curve is helpful in figuring this out. You can take an educated guess from a single impedance curve but if you can get separate impedance curves for the woofer section and the mid/tweeter section even better. The phase is also a factor here but let us leave that out for now. As the impedance rises the current demand to achieve the same SPL is reduced (assuming linear amplitude response from the speaker). Since the standard impedance curve rises with frequency it follows that it requires less power from the amp to drive these higher frequencies. So if you own more than one amp with the same gain but different power levels you should drive the mid/tweeter section with the smaller amp; or in the case of an LFR, drive the rear channels with the smaller amp. You can get a quick answer to what the amp differences should be by just dividing the higher impedance by the lower impedance. So if the rear of the LFRs are running around 10 ohms and the front around 4 ohms you would need 2.5 times the power to the front (10/4). An ADA1000 for the rear at 250 watts and an ADA1500 for the front at 650 watts works out pretty well.
