...has there been any documented evidence that these cadets have been involved in any more incidents than a standard pilot has been?
No. There is no documented evidence. Wanna know why? Because it's not in the airline's interest to do the research. They'd look like dills if it came out that cadets in fact WERE involved in a greater number of heavy landings, Captains taking control, bank angle warnings, etc. No longer could they hide behind their bold statements about cadets being just as safe as everyone else. No longer could they base their recruitment plans on two arms, two legs, a pulse and a wad of cash.
The other issue of course is that they're simply considered a 'pilot' once checked out and so very little data is kept as to their background. It's all put down as 'total hours'.
I do hear of people citing 'research' that points to bad habits in skills of non cadets but I've yet to actually read that research. Strangely, that research tends to be quoted by purveyors of cadetships. However, we're not just talking about the ability to 'stick and rudder' an ILS to minima, any monkey can do that. It's about controlling the fear that comes with not much fuel and an aeroplane all over the place and THEN sticking the ILS that is the real trick. Of course, many pilots with lots of experience use that experience to avoid having to be 'aces' in the first place but at least they've seen it before for when it happens.
Everyone is coming to the conclusion that cadets are worse pilots than existing/experienced ones but I'm just curious if this is in any way a proven fact or just an assumption that everyone is jumping onto because it supports their own point of view.
Lol. The naivety of youth. It's a proven fact that lack of experience leads to situations that require superior skills to get out of. It's a proven fact that sometimes superior skills aren't enough or the others supporting you don't have them. Air France proved that not long ago. So did Colgan before that. Heck, even the recent Safety digest shows what happens with a combination of poor training and poor discipline come together.
So arguing about whether it's an assumption or a fact may make you feel warm and fuzzy but for those of us who do this for a living year in, year out it really doesn't make much of a difference. There is NO substitute for experience and when you fly with someone who lacks it, you are going to have to be extra vigilant. That my friend, is a fact.