I learned to ride in an Aussie; the poleys do help you feel more secure. I ride a 17 inch, I'm about 5' 7" and 145 lbs. Wish I still had that saddle, broke up with bf and he sold it without asking.
I found that the position was similar to a dressage saddle, which is what I have now. One thing I didn't like about some Aussie saddles I tried, there's a slope upward to the pommel, which is hard on the female anatomy. I chose a saddle with a flatter seat. My guy friend agreed that the flatter seat was more comfortable for him, too. Note: I hate western saddles. I do not sit with my butt on or against the cantle. Give me an Aussie or an English saddle with knee pads any day, much more safe. Oh, one more thing; if the stirrup straps are English-style, you may need half-chaps or high boots, they can pinch your legs. Enjoy!