I only have an FM for an AS355 to hand, but this prohibits voluntary AR to the deck. It strikes me as being a risk-based issue. Given the high cost of twin engine heles and the fairly low frequency of needing to deal with double engine failures, the risk of training to the ground is not worth the benefit.
It is interesting to compare the situation for twins with SE. I would be unhappy to fly a single without being current on FULL EOLs (i.e. to the deck), but I am reasonably comfortable with the idea of not doing them for twins, as long as the entry and glide are practised and current.
As to whether there are more problems with autos on an EC135, I am not sure. The NR is certainly lively.
SIMs certainly sound like the answer, so long as they are a reasonable simulation of the real thing and aren't prohibitively expensive. Does anyone know whether the sim to be operated by Bond at Gloucester will be able to do this sort of thing like the real machine?? My guess is that it was mainly directed towards IFR training.