Great tool for silent recording of tube amps. I've compared it to a simple resistive dummy load and The Captor provides a much more lively or "real" tone for the recording.
However, there is an issue with the internal fan. It is powered by the speaker signal. When you strike a chord, it starts to spinn up with a bit of a delay, making a bit of noise. If you're playing very loud or with closed headphones, it's no problem. However, if you're playing at low or moderate levels, the noise is very distracting. It reacts to your playing but is not in sync with your tempo.
I solved it by using a long speaker cable and placing the Captor in a different room, so I can't hear the fan noise. However, the fan issue does reduce the score.
The speaker simulator could probably be useful as a backup in a live situation. For recording, I will use digital IR-based speaker simulations.