Perhaps it's worth explaining your situation. You're fully aware that while the Genie DVR is a great piece of equipment (starting the conversation off with a positive), no equipment is ever 100% perfect. And if the Genie DVR goes out (for whatever reason), then all of the minis can no longer do anything, meaning that you the customer are out of programming for the length of time that it takes to get a new Genie in place (which could be days, and would require another call to DirecTV to, at the very least, comp your bill for the outage). Therefore, that is why you have an ask for an HR24.
Barring that, there's nothing wrong with asking, "Can DirecTV help me out in better understanding how I could create another 'backup' solution in the event that my Genie DVR would go out?" Unfortunately, you really can't ask for programming credits; they're already doing that. However, I would push to get that initial fee down, or perhaps even requesting a non-DVR HD receiver (though I think that would be pretty extreme and would go against our recommendations on this forum).
I think you're wise, though. I would either contact a supervisor or to "Retention" (I think it's called), even though you're not a customer yet.