I would however like to hear why people are against doing this??
The school is essentially borrowing money off you.
Now, you wouldn't pay them up front unless their rate-per-hour for people who paid up front was sufficiently lower than then rate-per-hour for people who pay as they go that you were going to be better off, would you, ie the discount on the hourly rate is the interest they are paying you for borrowing your money.
Plus, given all the stories around of flying schools going bust and taking their students' money with them, you're going to want a bit more to cover the risk, aren't you.
So, in order to get anyone to pay up front, the school ends up having to offer a discount to up-front payers which is
more than the interest they would have had to pay had they borrowed from a bank instead.
There's only one reason they would pay you more money in preference to paying the bank less money, which is that they've already tried the bank and the bank refused to lend them anything because their finances were too dodgy.
(This is roughly what I posted last time we had this discussion and nobody has pointed out any flaw in my logic or arithmetic.)