Success. The 64-bit packages work with my AD installation when server signing is required by the domain controller. SSSD debug output here: http://pastebin.com/B7D1WDm2. No error or notice messages were logged on the domain controller.
Do you need anything else tested? I'd be more than happy to maintain this test machine (and a 32-bit architecture) for future testing if the community finds it useful. Let me know.