Ok, an update & correction to my earlier posting...
Went to seek a second opinion from a shop which claims that they specialised in installation/conversion of Mercs for the local tropical climate condition here in Singapore. Mechanic was against the conversion to electric fan(s), claiming that the current draw is high, among other factors. In his opinion, a proper functioning cooling system with 1 visco fan and 1 aux fan should be up to the task of cooling the engine even in extreme start-stop conditions. He took sometime to check through the entire system and found that the aux fan was not switching to high-speed mode, though the low-speed works. Changed the aux fan switch, changed a resistor and re-wired the system (car was a parallel import, hence was not equipped with aircon originally and whoever wired the system earlier obviously didnt do a proper job). Initially, aux fan ONLY comes on when the aircon is turned on, which is not correct.
Engine coolant temp is kept to just a hairline above 80C, irregardless if the engine is idling for an extended period (under the hot sun), cruising, after several hard runs, etc. So now, I stand corrected about the conversion to electric fans. For those thinking of converting to electric fans, it may be better to check through the system before doing so. One thing about the aux fan, when it switches to high-speed mode, its LOUD!... no mistake about it.. and the airflow is significantly higher.
Badinfo, my car is equipped with only 1 aux fan in front of the radiator. The fan is pretty big, there's certainly no space for another, unless you are talking about 2 small aux fans.