Lots have been said here about the perceived benefit of learning aerobatics in a low powered aircraft. If you want to fly lower powered aerobatic aircraft then I would agree. If you want to fly more modern ones such as Pitts or Extras then I don't think its that helpful.
The biggest problem is the time taken to climb for more energy after a few manoeuvres. I have flown a C150 Aerobat, many figures needed a dive for speed first and then a significant amount of time to climb afterwards, particularly two up with an instructor.
The situation is better in a Bulldog or T67, but still not as good as a Pitts or Extra 200.
So, a sortie of 10 practice figures will take much less time in an Extra or Pitts and therefore despite the hourly rate will probably cost similar.
Depending on where you want to go next should influence your decision. If its competition or display aerobatics then the Pitts/Extra route is better. If its just loops and rolls on a Sunday afternoon with friends, then train on the aircraft you will be using.