I believe most if not all western pilot unions are very much in favor of more upset recovery training. However, usually with a few caveats. Like real datapoints of the production aircraft outside the normal flying envelope to generate a truly representative simulator model. Training in the simulator on the type flown in normal line operation, not on small single engine piston aircraft that do behave quite differently from the aircraft for which said training is aimed, and have a very different envelope as well.
Skills learnt in an Extra are not necessarily transferrable to an A380.