In my own tests: the Full Res gives a definitional clarity to space that Reverb can’t easily approximate without some effort. You hear it in ‘phones or Near Field monitoring at low or moderate volume. As the volume goes up to rock performance levels, the sound of whatever room you’re in takes over - for better or worse, depending on the actual room. Whether the Full Res room plays well with the actual room is an ad hoc circumstance, but generally: probably not.
It’s also subtly noticeable in the response or feel aspect of playing: Like playing dynamics - you can’t hear the nuance of the feel of playing dynamics in a recording: you just hear the resulting tone. In the same way a recording of Full Res doesn’t entirely represent the feel of the space you get when playing it.
I’ve made a few efforts out of curiosity to get something similar to the room mic IR responses as well. Basically, tailoring reverb to emulate room mic. My best effort is with small room or large plate, a leaner reverb response than what I would typically use as an effect, with a clear sense of a reflection and minimal diffusion, and a definite sense of a tail (decay) - a quick clear snapshot of the (imagined) space. Not that it sounds good up in the mix, but it does sound more like an amp in the room mixed in down at -9db than typical reverb. There's a need for pre delay to approximate the distance of mics from the speaker (= .9ms/ft), and also the distance to the reflective surfaces of the room and back to the mic that have to be accounted for: In any case, while its possible to improve one's game substantially by doing a better job of crafting reverb to emulate room mics, it becomes evident that IRs of room mics are a smart way to go in recreating spaces that read as authentic.
In any case, Full Res does not replace Reverb as an effect, but it does allow greater potential from Impulse Responses. The Full Res is a more specific space, whereas reverbs tend to be set up to sound like more generalized spaces. Full Res also doesn't change the utility of, or obsolete the vast libraries of conventional IRs we have, as those captures tend to get the speaker and cabinet before the room comes into the signal. Room mics provide the room. Full Res has the DSP muscle and extended time to make it work. Full Res plus High Res Reverb are worth exploring on Acoustic Guitar: just getting into that now.
Anyway, it was interesting to muck around with a bit. Going forward, I'll be taking the easy road by getting some Full Res IRs when they come out, I don’t have a quality room worth recording or the inclination to roll my own. For those that can't make use of it (for now) it may be well worth your while to work up reverbs that give a more specific sense of space. Alternatively, playing in a good sounding space, you may not want to use them.