1. I do--I actually use it exclusively for my modelers. I bounce between my Matrix and LXII, but I (begrudgingly) prefer the LXII. I say begrudging because (a) I've had less than stellar experiences with Fryette's Customer Service, and (b) I'm on my second LXII because the first one suddenly dropped the output on the second channel. May have just been a tube, but the unit was two weeks old, and I wasn't about to drop money on (at the time) over-priced tubes to
maybe fix my issue.
Back to the sound - the LXII plays best with Fractal gear, IMHO, because you have more control over the Power Amp simulation. I set the Speaker Impedance Curve to Resistive so as to not overhype the highs or lows; and I keep the LXII Presence and Resonance controls disengaged. I also tweak the Speaker Compression and a couple other parameters based on the guide
@yek published on the FAS forum. On that note, you may be aware of this, but the LXII Presence and Resonance controls are internal trim pots that are a
PITA to access if the LXII is not fully out in the open. The PS100 in better in this regard, because you have easy access to those controls, should you want them.
When my buddy comes over, I love running both of us through an Axe or FM9 and then using the LXII to power his "amp" and my "amp." Both channels have a dedicated Standby switch, which is mega convenient. I wish the Matrix had that. When I'm playing solo, having the stereo LXII is fun for bathing myself in sound through four cabinets.
2. At one point, I had the Axe and LXII in a 4U case. It was an "amp head" in that regard, and I had no issues with things getting too hot. At least, not hot enough to trigger any sort of thermal protection. At another point, I had the LXII in a larger DIY rack case, but I had my amp switcher installed directly above and my Axe directly below, with more equipment directly below the Axe; and again, no apparent thermal issues.