In reply to:
Yes foof, that is exactly what is meant by a quasi or tapered crossover.
Well, I would say it is purely up to Ian and gangs' design decisions. There is nothing special or novel about those types of crossover circuits; just a bit more additional capacitors/inductors/resistors involved. I am sure that Ian has tried those designs as well during various development phases of his multi-driver designs. Besides the cost of the additional passive parts, those designs will inevitably introduce phase shifts between the identical drivers and other potential negatives right in the middle of the woofer frequency range. My guess is, unless his listening panel hears a clear benefit of such crossover designs, he would not incorporate them just for the sake of "coolness."
