I disagree. Components without cases are passively cooled. The HR-20 receiver has an 80mm fan cooling the underside of it's internal drive and with no lid the rest of the components are passively cooled. As for ESD ? Well there is no carpet in the room and no one touches the components, so I can't imagine any ESD getting in there.
Theres a big difference between a chip or disk laying in still open air and one thats in an enclosure thats pressurized, blowing hot air out, and creating turbulence in the case to actively cool it. But I'm going to go out on a limb and suggest that even though you're experiencing product failures with these approaches, you're not going to change your mind.
Further, unless you have rather high humidity, what floor covering you use doesnt matter much.
Obviously I dont recommend that anyone else uses these methodologies.
As for renting the receiver, well it's true what you say but we intend to use it until it's obsolete, so by then no one will care.
Maybe they wont. You might also experience a receiver failure and have to return it for a new one. Like I said, hope you have the old hard drive and hope you didnt do anything that is obviously detectable.
Again, unless you understand the risks associated and are willing to assume them, not recommended.