It's real benefit is the reliability - BUT - it based on a unique file format, so you convert between it's native format, and .wav. So feed it 24 tracks of analogue and it records solid as a rock, 24/7. We never had any issues - we had a small SSD plugged in via USB and the system just worked. Limitations were that in practice, how many control devices you were running - we had the drummer with an ipad and footswitch to start, I had a pad too so I could see what the drummer was doing, but when the keyboard player also tried to get in on it, it was too easy for the drummer to just be about to hit play, and the keys player would do a hamfisted prod, trying to shift the cursor down the list and the drummer would not spot the cursor had moved. Leaving starting and stopping totally in the drummers hand with me just looking for security was brilliant. To make it work, you install an app on the computer - we'd do the tracks in cubase and export them, then load these into the app and save them to the SSD, this would plug into the rack unit and that was it. The rack unit just looks for the playlist in a pre-prepared state, loads it and plays it.
We had a big problem - we always played live, but the keys player became ill and he lost the use gradually of his fingers - so loads of horrible mistakes where he's play a chord but hit extra notes. So what we did was take the tracks we recorded from the desk - a Midas M32 and they all went to cubase direct on a macbook - so we had all of his parts. He used an ancient Korg and with foot pedals has maybe three different sounds on the keyboard which he'd toggle through during the songs. So it was a simple matter to pull them out, slap them on the cymatic and then our FOH guy had say, piano, organ and sax sounds coming in, in stereo on 6 tracks - we had a click and an effects track too. That's all we used it for. A few songs he tried to play, and we left it up to FOH to let the audience hear what was best. Some shows, his hands were much better and we used them, but as soon as he started to hit bum notes, we'd switch seamlessly to the track. Very sad really. We decided, with his wife, that we'd not tell him that some shows the audience didn't hear a note he played. I think he probably guessed but we didn't ever say. It got worse very quickly and the outcome wasn't long coming. I think we used the system for just 9 months before he passed away. It did mean though that we were still playing almost up to the end. We decided that we didn't want to carry on - so the band retired.
The worst thing about the Cymetrix was that it only had multipin ins and outs so you had to use spider fanouts. They used the Tascam connectors and same wiring - but they're really expensive. I guess I should sell it, but I never have. For panto or other stuff, it's normal to have two macbooks, two drives and a USB switch box to hotswap if something happens, but we just didn't want to rely on a computer - we wanted something in a rack that would just power up, and work, and not rely on the net and updates and licensing.
In that 9 month brief period it never ever let us down. Our drummer now plays for a different band and they use exactly the same system.