The Kick version is an IB/door mounted optimized midbass driver. Its not designed to play below 80hz 12db, but excels in the 80hz-160hz kick area output and fidelity wise. They call it a 'constant Q' driver for its ability to yield a QUALITY FACTOR IB of 0.7 in ANY DOOR. Its a high Qts/very low VAS design. Essentially with 15 liters of airspace it can yield a Qts of 0.78 , and with 100 Liters that value is hardly affected to 0.71! Now this is a specialty driver IMO. Theres no hit or miss with this driver, performance is optimal from car to car, door to door. The midrange is not lacking either, it plays up to 2400hz 18db on the Rainbow passive and its consistent withthe midrange qualities of the Profi line.
The standard driver is a wonderful driver in its own right, but technically a standard driver. Natural midbass and smooth midrange. Rainbow sound. You can play these a little lower than the KICK allows you to if thats a concern. Overall good performace.
The phase plug driver is just that. A phase plug driver, yield the highest midrange detail and bass precision overall from a sq purist point of view- but its best enjoyed in a more on axis approach -say a kick panel to enjoy its capabilities. Its parameters dont show it to be the optimal IB performer the other two are for door use, and that typically affects output/response on the lower end compared to the other two.