This is an interesting question, and one which I've seen pop up in another forum. I myself considered the Plitron medical-grade units until I got my feet wet and did a little more digging.
One thing which I feel must set Torus apart from most other options is mechanical noise. I'm not aware of anything out there in the world of iso-transformers that can match the DEAD SILENCE of the Torus units under ANY line conditions. I've had first hand experience with transformers designed for computers (OneAC, Powervar) and have read many comments about various other units (like Topaz and even some Equitech). Seems that some people luck out and either get a "quieter than normal" transformer, or their power just doesn't insult the transformer so much with DC offset or whatever else causes mechanical hum/buzz. My last OneAC isolation transformer (a 12amp unit, CB1115) was suprisingly loud. I was using it in a smallish bedroom and there was a constant hum audible throughout the room. Not so bad when music was playing, but for quiet passages or movies I found it very irritating. Yes, I could have modded it to be quieter, but I suspect it never could be completely silent.
One other thought - Torus also oversizes their transformers for current delivery, so it's possible that you would need a larger medical PIU to get the same/similar performance.
