BP, do please remember that easyJet copilots will have had at least some previous asymmetric time on aircraft such as the Seneca or DA42 - whereas RAF ME students will not. So they must surely be given at least some asymmetric training on the Phenom; not a V1 cut at MTOM, but certainly some asymm handing, asymm approaches and go-arounds at training weights.
Way back when I first flew the VC10, we had a very basic sim. So pretty well all asymm training was done on the aeroplane. Such as a simulated 3-e t/o with a further failure once the landing gear had been raised, followed by the FI throttling back the 2 live engines 'to simulate Nairobi on a hot day'. Barking mad and very risky in today's culture. But when the improved simulators arrived, student captains only did one brief double asymm exercise in the aircraft. 3-e work was also reduced to the minimum deemed safe and we even did IRTs in the box later on. Which was a $od as the box lacked the upgraded aircraft instrumentation - no FMS RDU, for example.
High risk asymm should really only be taught / practised in a FFS, but at least some ab initio asymm work must still be flown in the aircraft.