On the 4.3 based roms there still may be some legitimate signal /data issues.
On 4.2.2 aosp ROMs the issue is mostly cosmetic, you have the same signal, but the ROM show you less bars.
Check out signal in phone status before assuming you are getting worse signal.
There are still some issues with data handoffs in aosp, but it isn't as bad as it once had been.
Sent from my SCH-I535 using xda app-developers app
Samsung Galaxy S3 Verizon SCH-535
AOSPA Notta 12/8