You keep going on about it being potentially lethal, as though utilizing a balanced power scenario is something that is going to be jury rigged without any oversight.
The BP boxes we have available for the 120V market are all design tested and approved for audio equipment use, and of the 2-3 main brands out there, most have already seen a lot of studio use. I've not heard of anyone dying from using them.
I mean...seriously...there is nothing "lethal" about using them, not any more than any other electric device.
AFA the 240v usage...again, if there are design tested and approved BP boxes out there for 240v use, I wouldn't concern myself about using them. If there are not...then it's a moot point talking about it being "potentially lethal".
TBH...I would trust a designed/approved purpose built device more than jury rigging common ground lines and/or augmenting your power supply in some non-typical way in an effort to minimize hum and noise.
AFA the cost...well...it's kinda relative to how bad someone needs a solution. You know...we work hard just to see a 10-15% improvement.
AFA the OP's patchbay questions...the only reason we segued into the power discussion was because of the whole grounding/ground loop stuff that was brought up. I don't think most home rec folks need to employ a balanced power system for a handful of outboard gear and where they mostly work ITB. I was just saying that a balanced power system *can* help with those issues, as another alternative.