The baby Perlisten is a speaker designed to be used as a satellite with a subwoofer, not a bookshelf with a port bump to try and make it sound like it has bass.
Also put in perspective the values in these linearity charts are +0.5 and -0.5 to -0.75 dB, the scale is intentionally small to magnify the differences because if they were on the same scale as the 2034 graphs you would be hard pressed to notice them.
Many speakers have similar or greater tolerances between drive units than the differences seen here.
This is not meant as any criticism of Erin's testing which is great but some perspective is needed when analysing them if anyone thinks these results are poor.
So the Perlisten S4b will cost around $16k with a pair of matching subs, to which you need to add amplification and streaming taking the total cost well above that of the 8C which includes all of the above. You also need DSP to optimise the S4b in your room.