The medium-speed mode of the fan controllers may come in handy if you need to cool your components better. However, this is done at the expense of your acoustic comfort. The Antec P193 V3 is the only system case to be more or less comfortable in terms of noisiness in this mode. The other two products won't satisfy you at such settings if you value silence.
Antec Sonata IV (medium)
The extra 500 rotations per minute of the system fan improve the temperature by a few degrees compared to the low-speed mode. The HDDs benefit the most from the increased cooling. Their temperature lowers by 4°C at high load. The rest of the components, including the HDDs in idle mode, get cooler by a mere 1-2°C.
Considering that regular desktop HDDs are going to be cooled well enough even at the minimum speed of the system fan (the Sonata IV is obviously not designed for server-oriented WD Raptor disks as it has no means of suppressing their noise), increasing the speed of the fan is hardly useful for it.
Antec P183 V3 (medium)
The P183 V3 benefits even less than the Sonata IV from switching to the medium-speed mode of the fan controller. The temperature of the hottest HDDs in the bottom rack only lowers by 1-2°C. The CPU benefits the most from the increased fan speed: its temperature gets lower by 3°C under load. Well, I don’t think this negligible reduction in temperature can justify the considerably higher noise level.
Antec P193 V3 (medium)
It’s different with the Antec P193 V3: this system case doesn’t get much louder after switching to the medium from low-speed mode whereas its cooling efficiency increases much more than that of the other two system cases.
Particularly, the HDDs in the bottom rack get colder by 6-7°C, the chipset is 4-5°C colder, the CPU and the graphics cards also benefit from the increased fan speed when under load. This mode seems to be optimal for the P193 V3 in terms of noisiness (which isn’t very high) and cooling efficiency (which is considerably higher than in the low-speed mode).
The next diagram compares the system cases at the medium speed of the fans with the open testbed: