Linkwitz W Baffle End Correction

In re-reading Linkwitz I find that he discusses pipe end correction but does not use the correction in his calculations for W woofer Peak Frequency calculations. As a result his peak frequency predictions are way high. So, my first question is, should the end corrections be used to get closer to the actual Peak Freq when starting a design? It would make initial set up of a DSP way easier. If so, any suggestions for getting it closer to reality? Any thoughts? Any measurements?

Secondly, I found that he does not discuss time alignment between two opposed drivers in a W baffle. It seems that if the drivers are opposed to minimize 2nd harmonic distortion, their voice coils are in no way time aligned. There should be less distortion and a better crossover to the midrange if the drivers are time aligned to each other. Any thoughts? Any suggestions? Any measurements?

Thanks.