I was kinda surprised that the Stevens are PAish drivers. The look like the bastard child of a PA speaker mashed up with a "real" midbass driver, but the FS isn't there. Maybe the idea is to jack up ~40hz on the EQ by 3-4 db to increase lowend output, but without the proper DSP, that's gonna create issues with substage. When he still owned ID, alot of the HLCD guys were running PHL's high efficiency drivers to keep up with the HLCDs. But those guys tended to be into high end SQ, competitions, etc, so they would have a substage & know how to get it blend properly with whatever midbass/range they were running without pulling the midbass to the rear of the car. Usually meant stepping up to 8" drivers too, which presents another set of problems. And they had processing power to deal with the issues that arise from running PA speakers in a car. That said, those probably work for the average daily driver that tend to have high crossover points (not filter points, the actual crossover frequency).
For the general public that's just looking to drop some speakers in the door, HiFi oriented speakers and power is much more logical solution.