I have both the HR10-250 & HR20-700 hooked up to the same TV. Is it ok to stack the 2 DVRs on top of each other? Will there be any kind of a heating issue? I see that the HR10-250 has a fan in the back, while the HR20-700 has vents on top. So I figure I should have the HR10-250 on the bottom and the HR20-700 stacked right on top of it so the HR20's vents are clear. Is this ok? Also, I've had the HR10-250 for a few years now and have never turned it off, unless it needed to be reset. The HR20-700 has an actual "off" button on the remote. Should it ever be turned off? Should it be turned off regularly? And will recordings and software updates go through as scheduled if I turn it off?