I know!.. When I saw the Pic of your girls rig I had a weak moment and started to try to figure out what my size would be. I was thinking of making a Sirrus tribute bike out of one.. Peel off all the Surly Stickers (Well, maybe I'd keep the FFF sticker. Then apply the sticker scheme from an '88 Sirrus)

I was confused due to the spacing of the top tube, down tube, and head tube meet with a similar gap to my '88 Sirrus which is a 47cm.