I vertically biamp too - pretty common, but does not accomplish (ie as you believe) what an active crossover does. It's true that both sections receive a full 200 w/c, but they are ALSO receiving the full bandwidth of your preamp (ie 20hz - 20khz). The active crossover will ONLY send bass frequencies to the woofer, and ONLY send mid/high frequencies to the mid/tweeter. Thus, each channel is only amplifying those respective frequencies. In my case it's not worth the expense of an active crossover, but if you're after a truly high end system you would have to do that.
I have tried passive biamping both vertically and horizontally in multiple systems and multiple amps, and there's only one case where I noticed a difference (still using it today). It's very speaker (and probably other components) dependent. Also, many argue you're better off not biamping but instead investing your $ in one better amp (ie than your EX-442). There's likely some merit to the argument, but I have not found one "better amp" for 2x the cost of mine . . . so there's that.
In any event - you already have the amps - go crazy with biamping.
I have tried passive biamping both vertically and horizontally in multiple systems and multiple amps, and there's only one case where I noticed a difference (still using it today). It's very speaker (and probably other components) dependent. Also, many argue you're better off not biamping but instead investing your $ in one better amp (ie than your EX-442). There's likely some merit to the argument, but I have not found one "better amp" for 2x the cost of mine . . . so there's that.
In any event - you already have the amps - go crazy with biamping.