Giles, I don't know how wide and varied your experience is, but over the last decade I must have flown with a couple of hundred different FOs, albeit some of them just a few times. What I can tell you is that there is no discernible pattern of who is good and who is bad based on experience. I have seen some very poor high experience guys and some excellent cadets, as well as vice versa. The one reliable factor is attitude - there is a specific demographic that has an arrogance issue associated with low experience (with exceptions of course), and they are the ones that can cause the most problems through distractions and frustration of other crew members. It's not that they're cadets that creates the problem, but a problem with their earlier training and also their culture and motivation in become a pilot in the first place (prestige and show boating rather than a love of flying).