http://www.juniper.net/us/en/local/pdf/validation-reports/eantc-mx-marketing-report.pdf
1,000 L3VPNS with 1,000,000 VPN routes @ Line rate forwarding
500 VPLS instances with 20000 MAC addreses @ Line rate forwarding
It would have been much easier to find if this was in the product data sheet, but I suppose that would too much additional work. Maybe they have othere reasons which we do not know of, but it would still be nice. On the other hand, you have to look at the test bed to get a realistic idea. Often what is used in lab test simulations would not be able to adequately emulate a real world situation because admis would use CoS,m firewall filters, routing policers etc which would surely affect the performance. But that number is still not the maximum the device is capable of supporting. It could much higher.