the 1.6 build has intrid.gz for jailbreak installed. It is located in zimages/ps3jb on the root of the sd. when you setup jailbreak it copies and paste the initrd.gz from zimages/ps3jb to the android folder.
thats what i am saying.. i think the android build can't boot when initrd.gz is replaced with your one as they have developed new initrd.gz recently which improved performance drastically.