The 64-bit may or may not be a big deal. I'm actually pretty worried some 64-bit devices may never run app_process32 in privileged mode, at which point the hook to start the su daemon fails. The 64-bit builds expect to chain to app_process64 instead.
Use of app_process to hook in is obsolete and not recommended. As long as the device is capable of executing a 32bit binary from an init script, there should be no advantage to 64bit builds.
The 64-bit may or may not be a big deal. I'm actually pretty worried some 64-bit devices may never run app_process32 in privileged mode, at which point the hook to start the su daemon fails. The 64-bit builds expect to chain to app_process64 instead.