Lman,
If the Vector is not an option for you, then the Switchblade would be my recommendation. The SB has great low end power so it maybe possible that a 9m SB fits better in your Ion quiver than the 10m. I am not familiar with the Ion's so it will be worth investigating.
The SB is a very forgiving, smooth stable kite and thus is appreciated by all levels of riders, big and small, male and female.
The IDS safety system is excellent, and easy to use. The 2011 QR1 is very easy to activate and reassemble.

Mike Minichiello owner and operator of Kitehouse Cayman has been using Switchblades to teach his students from scratch for years.