Okay, the proposed radiator scenario was using a 120.2 with 2 x 30-35dBA fans on it.
If we consider say a 4 x 12cm fan capable radiator, with 4 x 35dBA fans on it, we would probably get a C/W vs flow curve like the 2 x 120.3 radiator show below (the pink line). The 120.3 in the plots below are assumed to have 30dBA fans on it, but if we assume 35dBA fans on our 2x2 radiator, then using the pink line is probably a pretty fair approximation. The HE radiators do have a very low pressure drop already, and a larger heater-core isn't going to change this much. The bulk of the pressure drop from heater-cores comes from the barbs/fittings, and not so much the internals.
Okay, so let's re-assess the 60Hz 20RZ vs the 60Hz 30RZ using those figures:
Iwaki 60Hz MD-20RZ, 8.7 LPM, 0.015, 0.159
Iwaki 60Hz MD-30RZ, 11.7 LPM, 0.014, 0.155
20RZ => 0.159 x 100 + 0.015 x 131 = 15.9 + 2.0 = 17.9C
30RZ => 0.155 x 100 + 0.014 x 163 = 15.5 + 2.3 = 17.8C
Factor in that the room would have a C/W itself of roughly 0.003 for a typical 3.5x3.5x2.5m office-sized room, and the extra 32W of the 30RZ makes the room 0.1C warmer than the 20RZ, and we're still back at pegging even once we factor in the increased ambient temperatures.
So you've gone and stuck in a 100W pump, a HUGE 4-fan radiator with 4 moderately noisy and powerful fans all at once, all added together for a total of 41-42dBA noise levels, and still even in this stupendously high-ended radiator scenario the MD-30RZ @ 60Hz only ends up just matching the MD-20RZ.
Talk about trying to drive a tack into two small pieces of wood with a jack-hammer...
Have been saying the same thing for well over a year now. There is absolutely NO point to ever consider buying/using a pump that is drawing over 50W of power, almost totally regardless of your situation. None - except in the very rare circumstance that you're drawing your water from a nearby flowing mountain stream, or using a swimming pool as a reservoir/radiator.