Hi
I am sorry perhaps this was said before in this long thread (I did not read it entirely) but I would like to say something that addresses the reasons.
It is an unfortunate fact that a fresh unexperienced pilot does better in terms of training performance on a fast commercial EFIS jet. These are just cold statistics and many ex-turboprop captains fail line training as FO in our company.
I personally flew with an FO coming from a lighter jet with lots of hours as a Captain and he, as well had a lot of trouble catching up with what was going on.
I really don't want to generalise or speculate why, however it seems to be a totally different set of skills and thinking that is required.
Another reasons is psychological - many super-experienced turbo-prop captains come onto the A320 flying with young un-experienced captains and getting severely frustrated by their own under-performance and position.
We are not really pilots, we are (computer) managers and the flying is like being a robot, except of the few situations you are suddenly required to think outside of the box (that's where the experience would be helpful).
However 99% you are required to be a good-functioning and precise robot, knowing the SOPs down to the last letter and applying ready solutions to highly-typical situations.
If you are desperate to get onto a jet - lie, throw away your logbook, and play low-houred cadet ready to learn - if you are able/willing (why would you want to?) to adapt to that.
I don't see another way in.
(Also tried to help many turbo-prop captains to get even a self-sponsored type rating and failed)
I'm afraid that's what happening to any industry as it expands: nobody wants a programmer who is able to disassemble some obscure old code now-adays. Companies want the programmers who know all the modern techniques and seamlessly fit into their computer factories.
That's what's happening I am afraid.