The last BMW bike I had ( not counting my 71 airhead project ) was a 2000 R1100R which was fine solo but a bit cramped with 2 up, and greatly affected by the wind in this part of the country. Very good bike in the twisties, but got blown around alot and top heavy when it was loaded up with a tank bag etc.
The Heritage is no BMW, but is a very good touring platform, if you don't mind some wind. Within its lean limits it handles fine in the twisties, but you soon realize that's not what the bike is really designed for. I've found the Heritage a very good all around bike, maintenance is a snap, and in my view keeping the Harley stock is the way to go.
If your wife is height/inseam challenged then she'll enjoy the softail family. Good luck on your search. Take them for a good test drive at a Demo day or borrow a friends.