After 500 hours you can't tell the difference between how anyone was trained. They can either do it or they can't.
Do understand though that there is more than one reason why airlines like cadets.
The first as Bealzebub states is that they get a known quantity through the door into the training dept.
The other reasons are financial.
They get quite large tax offsets against the training.
They get to claim the VAT back for the training.
They get to reduce the employer NI contributions for that employee.
Of course the company gets all that, the cadet doesn't get to see any of it and they pay the full wack.
Be assured if it was cheaper to get modular/open market in that's what they would be doing.
This is a well pedalled sales line from the big schools when approaching airlines to start cadet schemes.
Unfortunately the schools have been looking at the short term of bums on seats. They haven't realised that if they sow up all the "jobs" there is no point going for their product because there basically is no jobs which prefer their products which aren't already spoken for. At least before the cadet scheme's there was a chance that people could get one of these jobs so it was worth paying the extra to be in with a chance.
Now there is no point. Your only chance is Ryanair if not on a cadet scheme. 6 months out the door, your grades aren't the best or they just plain don't like you, and the school will wash their hands of you. Then your in the same boat as all the modular but with less chance because most of the smaller airlines the training dept and CP is from a modular background.