I think the need to convert to electric fan(s) really depends on driving conditions and where you are located. I'm driving a 230E (M102 engine) here in Singapore and I do experience high coolant temp ONLY when I get caught in a long traffic jams on a very hot day. Coolant temp stays around 85C during daytime cruising and stays slightly over 80C at night (both with aircon on). However, temp will start to rise if the engine is to idle for an extended period with the aircon switched on. It goes as high as about 110C. My cooling system is working fine (this is despite of using parts for the local climate conditions, eg. 71C thermostat, visco fan locks at 80C instead of 105C, etc.). This is a condition caused by insufficient airflow when the vehicle is stationary or travelling at very low speeds. The visco fan simply cannot supply sufficient airflow at idle/low engine speeds. I've seen some older W124s with aftermarket electric fans and the airflow is noticeably better (despite using a smaller-sized van as compared to the original visco fan). If you take a look at the newer Mercs (at least those that I've come across), they are only using a SINGLE electric fan and the fan size is smaller than our visco fan. Yet, these cars do not experience creeping engine temp towards the red zone during extended idle periods.
IMO, the electric fan should be a suitable replacement under the above conditions.