Discussion of these matters always seem to centre on cost. In my mind that's not the number one thing to look at - i'd rather look to the reason behind the cost savings. The major reason that the two types are so different in cost is the maintenance standards. We've done the sums and run a Gazelle, Sportstar, Warrior and 172XP among others. Basically if you're paying a competent professional to do the maintenance on your RA-Aus aircraft the cost difference is negligible. In reality the price difference comes down purely to the difference in fuel burn.
It's a simple fact that RA-Aus aircraft maintenance has little to no oversight. We all like to think that people are doing the right thing but that's not always the case. I was told by a student of a local school the other day of the school's entire fleet of 5 RA-Aus aircraft being grounded as unairworthy after CASA decided to look over the RA-Aus records during an audit. Worrying stuff really.
If you find a good school they'll proudly show you the maintenance logs of the aircraft you're flying and spend as much time as necessary explaining who performs the maintenance and their maintenance programs.