Personaly I would go try the 1.0, it's the 50mm's 50mm. While it's not quite as sharp as the 1.2 it's 2/3rd stops faster and makes a noticeable difference in bokeh and low light. Here is a link to a review by Juza http://www.juzaphoto.com/article.php?l=it&article=59 and http://www.juzaphoto.com/article.php?l=it&article=105. Right now the english version is down but you can still compare the IQ to the 85mm f/1.2, which is sharper than the 50mm f1/2 and the 1.0 is not that much worse.

Cheers,
John.