I used to worry about case sizes, as I have possibly one of the skinniest wrists on the Boards (6.25"). But now I wear the Ingy, a 44mm PAM and will soon add both a RO Jumbo and PP Nautilus Jumbo to my collection. They'll look big on my wrist for sure, but my feeling is - if you like it (and it feels comfortable), wear it proudly .
I visited Marcus today in Bond Street, London, which must be one of the best watch shops in the world. The layout, the collections, the aroma of serious money - amazing. A very friendly sales guy there was commenting on how watches are getting bigger and bigger, and that the trend shows no sign of slowing; apparently AP are planning a limited edition watch that comes in at 48mm! He also pointed to some Franck Mullers that make PAMs look small, and said that they're the most popular model with women at the moment.
So all power to big watches on small wrists - it's the future!