My wife choose the IQ RMK 600, and here was a few of the deciding factors.
1. Seat, the IQ seat is narrow up top, fits a woman better than the couch's on other sleds (wifes statement, not mine)
2. Balance, the sled overall does everything well, its easy to sidehill, easy starting, and has PERC
3. She liked the available features, (storage, etc)
4. Modability, lots of proven setups out there from companies like Carl's Cycle and others who have lots of upgrades that are resonably priced and greatly improve the sled. This was more important to me, but now try and take her Carl's valved floats away....... good luck
5. Price and parts service, we were able to get a better deal on the Polaris and parts from a dealer we are comfortable with.
I did say those things...and I agree-- Not just because he is my husband, but he is right. I think the seats on the IQ are easier to move around on, I didn't like the feeling of doing the splits while trying to ride. The IQ is easier to control for me. I also do enjoy the small yet useful storage of the IQ. I do realize that if you are looking at the 09 IQ, you do lose storage under the seat, which only leaves you with a small compartment by your right kneee, unless you decided to add a bag somewhere.
PERC--I can't live without my PERC-- My husbands mod sled doesn't have it and everytime we ride I ask him how long until he gets it. It takes a lot out of me to be dragging a sled off the trailer, I end up tired before we even start riding.
Ean is also correct about the shocks- wouldn't go back to stock if you paid me.
Does this mean that Polaris is the only answer??? for me, yes. For your mom--it is whatever she feels best on, try to get her on both in the same time frame and areas so she can compare the two. I know many women on here will say cat, that is fine as long as she is happy with it. The key is if she is happy, comfy, and in control of the sled, she will enjoy riding.