What’s the Right Power Amp Ratio For Bi-Amping?

Im bi-amping a pair of Tyler Acoustics Halo Extreme with an Parasound A21+ into the low end and an Prima Luna Evo 400 feeding the top. Rocket 88 carbon x speaker wire. The gain on the amps are within 3 db of each other. The sound and imaging space between the instruments is phenomenal. Im using an Cambridge Audio Cxn v2 into a Audio GD r7he mkii dac and Audio Research LS 28se preamp. Im loving it. 

With speakers that have seperate terminals for LF and HF, doesn't that remove the problem with both amps sharing the same load? Or does it not matter because the amp "sends out" the same signal regardless of what it is connected to?

For example, Tannoys have separate terminals, and Tannoy say they are biamp ready. Would they bother if they didn't feel there could an advantage? 

From what I understand the total out put gain needs to beof equal value or very close. If not the under powered will be drowned out. 

Why vertical bi-amp? You don't need the same power for the highs as you do for the lows. Horizontal bi-amping is much better because the low frequencies are not robbing power supply current from the high frequencies. The actual ratio depends on the efficiency of the drivers. Are you still going to use the internal speaker crossovers? With or without an external active crossover? Multi-amping has been in my blood for 44 years.