Are any of the core packages (those included by default on the image) written to be deterministic and thus would benefit from real time kernel support?
Not really, networking tasks usually work best without preemption (it won't hurt, but it won't help either).
User trippleflux on github did some work (see here) patching with the preempt/RT kernel and showed in at least one context, much improved bufferbloat.
I built the patch set on my x86/64 box but did not see any differences on the RT kernel vs standard for bufferbloat.
Preempt/RT patched 6.1.40: