Bi-amping my KEF R3 Meta speakers.

Theoretically the amp that drives the woofers has the challenge of physically pushing the woofer and dealing with all the electrical interactions from that task, so splitting that job gives the tweeter amp the benefit of not having the side effects of handling that task. Your situation is most feasible for a passive horizontal bi-amp configuration. Your two amp choices are relatively similar compared to say a tube amp, plus the passive crossovers remain unchanged, so I’d surprised if the difference is significant, but it might be audible.

How much change it makes is an unknown, but since you have both amps on hand it’s not a huge deal to experiment. You might find that one does better as the woofer amp, and the other on the tweeters, so try both ways if you proceed.

I had to look up passive horizontal as I was not familiar with the term. One source said it was often referred to as "fool's" bi-amping.

In light of what you say and what I gleaned from quick research, probably best to leave as is. My preamp has both high and low bass management. I currently have it set at 60hz so the amps in the subs are handling the low end and my other two can loaf along with stuff above 60 or so.

I'll continue to arbitrarily switch them to keep the juices flowing so things don't dry out. Thanks for the info.

Implementing powered subwoofers into your system is essentially active horizontal bi-amping, so you’re bi-amping already.

Sensitivity of both amps is likely different - you need to adjust signal levels.