Who cares? Listen to the speakers with your music at different volume levels, and if you still like sound what difference does it make if there’s a Doppler effect or not? There are ALWAYS trade offs between different speaker designs, which is why your ears need to be the final arbiter. I’ll also add that I think concentric drivers are time/phase coherent (or maybe one or the other) that may outweigh any Doppler effect. Let your ears be your guide. Personally, I think there are much more important speaker issues (cabinet, crossover design/parts, driver quality, etc.) than worrying about the Doppler effect. Just my $0.02 FWIW.
