It is a tuff one to say.

I've seen cat5 cable that someone installed with a bundle of Romex, wrapping around it, going thru the same holes, the entire run of cable (about 40-50 feet). Put a cheap HDBaseT extender on it and it worked fine.

Then I have a house I'll prewire with Cat6, keeping it away from everything, put in a good HDBaseT extender (tried a couple of good brands)... and every time the customer turns the lights on/off the picture blanks for a few seconds. *facepalm*!!!

I wouldn't think a 70V system would cause you any problems. But it's HDMI so....