I am getting in on this a little late, but here are my thoughts...

The Up's:
I have had 3 RBI RHP's for a few months now and for the most part I like them a lot. They do a much better job of keeping ambient temps up. Before I had the RHP's, I had to heat the entire room up to 82 deg or so and then had UTH's to heat a hot spot. As far as power usage goes, it is much less expensive to heat 3 cages then an entire room.

The Downs:
Here is the down side for me. I had the cages stacked and found that there was WAY TOO MUCH heat transfer from the top of one cage to the floor of the cage stacked on top of it. I was seeing floor temps of around 102 deg. Mind you this is through 1" of PVC (AP cages). I had to put 2" spacers between the cages with insulation in between in order to correct this problem. Just something to think about if anyone plans on using these in stacked cages.