This is an interesting spelling that has some appeal as it reminds me of the ending of philosophy-- well, philosophy is the love of wisdom and Sophie/Sophy means wisdom--but it would be annoying to correct people's spelling all the time. Sophie is prettier as well.
I much prefer this to Sophie (which I don't think ages as well)--however, I still prefer both to Sophia. I think Sophy is a great name that deserves to make a comeback.