Excellent choice. The two piece is really the best bet. Your lady may experience fatigue or shoulder injury with a full upright because they are moving the weight of the entire machine around instead of just the suction piece.
The battery ones suffer from both the weight shifting (although it is alleviated with cheap plastic and a weaker motor) and the battery problem. Oreck used to be a leader in the two piece but a recent check of their site suggested they are out of that market. Big mistake.
Your choice is serious and appropriate. Let's find you the best price.
$339.95 at best buy and amazon. I would suggest finding a local retailer and offering that in cash.