Hi Alex,
I did purchase my second standard actuator from France but it was out of stock at that time and I needed the crane to be ready before LEGO World in Copenhagen. To be on the safe side I ordered 2 with the alternative gearbox from Canada. They actually arrived before the one from France and they had been so kind to put in 2 extra gearboxes so I can change on my standard ones if needed.
When 1 alternative geared can lift the boom it should mean that 2 standard ones can do it also but to be on the safe side and not crash my gearbox I prefer to use 2 alternative geared.