If you biamp with stereo amps, separating woofers and tweeters, you can put a maximum of 8 watts into the woofers on each channel. If you use the amps as monoblocks the full 16 watts available from the monoblock can drive the woofers. The potential advantage of biamping would be more likely to show if the amps are being pushed hard. In that case the woofer amps would be likely to run out of steam before the tweeter amps and the highs would stay clean when the bass went into distortion. However if you have twice the power to put into the the woofer with monoblocks you are less likely to drive the bass into distortion in the first place. So from an overall performance standpoint monoblocking makes more sense.
To further refine the setup one might develop a system that uses, say, a single stereo Kaiju to run the tweeters and an even more powerful pair of monoblocks on the woofers. To keep things super clean between tweeters and woofers one could develop an active crossover that would divide the treble and bass before it gets to the amps, thus saving the tweeter amp from potentially being overdriven with bass frequencies when the level is set extremely high. This is not really necessary, but theoretically a little bit better than using the passive crossovers. It's possible that there is a system like this already. It's possible that it's in my listening room. The next step beyond this might be to use monoblock Kaijus on the tweeters rather than a single stereo amp. Jagers with 16 watts on each tweeter and for acedemic purpose let's say around 35 watts on each woofer array would make for a rather profound listening level.