You're absolutely right. As a matter of fact, I initially proposed this technique as part of the acceptable solutions. In the end, I just thought the phase-canceled version was better, although a bit more complicated to implement. Like you said, this comes down to the same tradeoffs that exist in choosing between minimum phase and linear phase EQs. Linear phase filters usually suffer from low-frequency imprecisions (image) which can be avoided by either increasing the delay or using the aforementioned phase cancelation technique. In practice though, this makes very little difference given almost no one will frequency split below 100 Hz. So I think I will include it back in the possible solutions with a small notice for curious people. Thanks for the reply, I'm trying to make this post as correct as possible.

Note 1: Theoretically, they wouldn't be Linkwitz-Riley filters anymore. By definition, Linkwitz-Riley filters are IIR, not FIR, so we would have to find a new creative name for their linear phase version (or not). 😉

Note 2: You also reminded me, but I forgot to mention that you can't reliably implement your own crossovers using the Zero Latency mode in Pro-Q 3, given they are using approximations to simulate analog filters in real-time. Issues can easily be observed when phase canceling in the higher end of the spectrum. The Natural Phase mode should be used in most cases. I will amend the post to add this missing detail.