Not sure. We tested it with my friend with even 2 gigs and still didn't work for him
I'd love to see the reports then, as using a 32x Java that argument worked perfectly fine.
What I DID accidentally do was use the Xms argument instead of the xmx, however JVM was smart enough to set min/max to that. It worked perfectly after that. I'd love to see if I can maybe help with this project.