Was out of town on a gig, so am a bit "latent" (Waka Waka) in further responding here, but this is what I found in my situation...
Was able to measure actual latency between a signal that was split and ran direct and the "processed" Axe-Fx signal of my Ultra (running a typical patch with amp block, two cab blocks, parametric EQ block, and reverb block)... Nothing too significant (in the <2ms range).
It turns out that my "perceived" latency was actually caused by the noise-gate being a bit slow to open and thus feeling a bit non-responsive. All good now.
Thanks again,
-Matt