Hi jpak,
Yes, ideally, one would linearize the drivers outside with speakers raised up. However, in my case of speakers weighing 150 lbs each and no where quiet outside, I ended up linearizing then in-room. In my eBook, I measured them 10cm away on axis and for sure, linearizing the woofer is going to include room effects. In my specific case, linearizing the woofers produced a better overall result than not. It is an experiment to try.
There is a caveat, and quick to find out if it is worth linearizing or not as it is an optional step. If the driver measures +- 2dB through its passband, in a near field measurement, then linearizing won't buy you much. In my specific case, I use compression drivers and waveguides, which typically have a little more ragged frequency response in favor of efficiency, so it was worth the effort. It may very well be that the Wilmslow K1 use much smoother drivers and you can bypass this optional step. A quick near field measurement indoors will validate whether you need linearize or not.
I use constant directivity waveguides, so no need to measure near field off-axis, which I did try and the fr result is as expected. Basically one is at the mercy of the polar response of each individual driver. Using linear phase digital XO's, which I highly recommend, will have minimal effect on the pattern control through the XO as the XO slopes are steep and both the amplitude and phase response sum perfectly as can be seen in the article you read.
Hope that helps.
Kind regards, Mitch