TSX is a nice car but you might as well look at the mazda 6 then since its cheaper and offers the same level of performance.
A RWD car isn't that bad in the winter, I've driven my father's 97 C230 in the snow, its tail happy but if u only give it a little gas its ok. Problem comes when attempting to climb hills in the snow. U'll get stuck even with snow tires in snow on hills.
She should get what she wants, if she wants an RX-8 get one. Worry about winter driving when it comes. If you live in the city like toronto, snow tires is more than enough (if you live in a hilly city, ur on ur own). Just don't go on during bad storms.