I guess that it is cheaper for a student pilot to fail on fixed wing than rotary. 25 years ago the Army pilot trained on Bell 47 G4 for 60 hours prior to transitioning to the Gazelle (120 hours) and then further transition to the Lynx, Scout or Beaver.
There is nothing wrong with training in a piston helicopter, provided that the right one is selected. The benign handling of the 47 instills confidence in the student prior to converting to the greyhound of the fleet, the Gazelle.
Twins are more expensive to keep in the air 24/7 but I still firmly believe that they are safer than singles, especially piston singles.
Sure there will be incidents involving tail rotor failures, MRGB failures and the remote chance of a double engine failure, but the twin still has to be worth the extra expenditure.
Single engine failure in a twin at night over built up area = fly away................single engine failure in a single at night over built up area = Oh !!!!!, we're going down!!!!!!!!