I've been working with an X-Load, a TwoNotes Captor, a Suhr RL, and a Rivera Mini Rock Rec, for the past couple months, recording a stereo wet/dry/wet rig with IRs I made of my speakers...
Reactive load technology isn't quite matching the response you get from an actual speaker load. The line out -> IRs sounds really good when the speakers are still connected, very close to the mic'd speaker sound. But disconnect the speakers and use the internal dummy loads, and the mids go flat. They don't have that 3D depth that is still there in the direct signal when the speakers are connected. The Suhr RL gets REALLY boomy and mid-scooped, and the X-Load UK voicing is very similar, though better than the SRL (to me). The US voicing is the best, not boomy and less scooped (which is strange because it says the US voicing has more bass, and US-voiced amps/speakers are generally more scooped with more bass than British-voiced speakers).
The TwoNotes load is close to the X-Load US voicing, and they make a good stereo pair for the wet amps. The Rivera Mini Rock Rec is too flat, dark, and boxy in the mids, not much different from plugging the FX send -> the IR loader. And the Suhr is way too bass-heavy and scooped for my Mark V (the preamp of the rig and the dry center channel power amp). So I connect the Suhr and Rivera in parallel for a 4 ohm load, and they balance each other out well enough, while using the slave out on the amp -> IRs.
The XLR output on the X-Load is very noisy with phantom power. Using a Samson MLI1 line isolator w/ground lift between the XLR and interface cuts any noise to guitar gear, but using an 18V power supply for the XLR output still adds noise/hiss. Not as much as phantom power, but more than is acceptable. It does provide the strongest signal of any of the load boxes’ outputs, but the noise makes it unusable. So I use the unbalanced output and more gain on the interface. I still have to use the line isolator for the ground lift, because all unbalanced connections have a ground hum without it. The TwoNotes XLR output is the only one that doesn't need an isolator or ground lift, and it's being powered by phantom, yet has no noise.
I get better direct recordings with my IRs when speakers are still connected to the amps, but that defeats the purpose of silent recording, and I do my best work late late thru the night.
With further EQ'ing, I am getting usable recordings with the reactive loads. I'd say the X-Load US voicing is my favorite of the 5 voicings in the 4 load boxes. The TwoNotes a close second. But the TwoNotes is the best overall single box, because it doesn't have any noise when connected to the interface.
The X-Load's feet are high enough for it to stand on top of the Mark V and Carvin V3 amps and clear the handle, but the Suhr is a tad short and sits on the handle on the V3 and wobbles. The TwoNotes doesn't have any feet, but is much smaller. The Rivera has the best feature set that I wish all these boxes had, but it has the worst-sounding load.
It is a huge disappointment and inconvenience that none of these boxes (except Rivera) have a load/speaker switch so you can leave the speaker plugged in and just switch it off. I have to squeeze in behind my tall, stacked-up rig every time I need to put the speakers on or off. The Rivera also has a 4, 8, or 16 ohm switch, which is versatile, but maybe has something to do with why it doesn't sound as good? You can also use its XLR and 1/4" outs simultaneously, while on the X-Load and Suhr, it's one or the other.
I just really really wish they all had a load/speaker switch. It was a huge oversight to leave that out.
