I really dont see why people in training organisations etc have to put a big cloud of uncertainity over someones career when they wish to make the transition from light twins to glass cockpit jets.
On the whole if someone can fly a light twin in IFR and dodgy weather conditions they can fly an A320 no problem. The only people who say that flying big jets is difficult I believe are some pilots who wish to make out that their job is much harder than people think and requires a lot more skill.
I fully believe that while an A320 or something similar is much more complex to understand in terms of the systems, to actually operate one is easier than a light twin.
The airline world is made hard by flying the aircraft close to its economic optimum. 30 years ago I think it would be a different story with many steam gauges found on the flight deck , but not today!