Just grabbed one o' these:
Sorry for the ginormous pic, but it really is a pretty pedal in person, and that's the closest Google image I could find to what it actually looks like in person.
Just tried it out for a whopping total of 20 minutes. Quick first impressions? Outstanding boost for a crunching amp!!!
Out of the box, I just left the tone, 100Hz, and Curve knobs at noon, left the gain completely off, and dialed up the pedal's volume to just shy of noon ~ sounded EXACTLY like the Plexi, only @ higher gain. Completely transparent boost, yet without the flubby bass I usually get from a dedicated clean boost pedal (as opposed to an overdrive). Messing with the other knobs and adding a touch of the pedal's own gain yielded a tone that was still very Plexi, but just a tad thicker in addition to being higher gain. Awesome. 
Gonna take a bit longer to find settings I like for running the Rhino as a drive pedal with the Plexi dialed clean, though. Out of the box, the pedal's gain sounded good & thick, but the eq (without tweaking) seemd a bit muffled ~ not muddy, just not crisp and clear. This pedal can produce some very, very smooth gain on its own, and I'm used to a more raw sounding low-to-mid gain tone. I think the pedal's eq is powerful enough, though, that I could get there with more tweaking, though. Maybe not totally raw, but a bit more "rawk" sounding.
In both setups, the Rhino stacks amazingly well with my Suhr Riot. I'mma hafta record some pseudo-metal clips with the Plexi set for crunch, the Riot kicking in the high gain, and the Rhino boosting the Riot.
