If your decision is based on being able to plant her feet on the ground better I would recommend looking at boots with thicker soles and/or a seat modification instead. A lowering method by changing the suspension may make for a less then desirable ride.
With that said, like everything else, you get what you pay for and if that is the route you will be taking I would look at the complete shock replacement set ups like from Progressive and others rather than going the inexpensive route using a simple lowering kit in hopes to maintain as much of the original ride quality as possible. But then again I am very good at spending other peoples $$
