Sorry for the delayed reply. As of now, there is no official AOSP support for I9500. Samsung didn't release the source code for Exynos 5. Until, Samsung releases source code, I9500 will only get mediocre CM builds. Speculations are that there will be a source code released some where near int he future. But the situation is not clear as of now.
I9505 on the other hand has a excellent support, as Qualcomm always releases sources for their SoCs