This isn't a question but some information to share with potential Regency CI1250 owners (or any other insert really). I got a lot of information on this site so this is my way of giving back and of course any feedback or issues in my installation are welcome.
I planned to re-tile my fireplace as part of this upgrade and was really focusing in the overall design as much as function. In my research I was getting really annoyed by the potential need for a backing plate. I was trying to find the right unit that would fill whole opening but I couldn't find one. Instead, I used metal framing and backer board to close up the vertical dimension of the opening by about 6 inches. The final result looks great and specifically this unit is really nice looking. So far the heat output is satisfactory. We haven't had a really cold day yet, but today it was 35 degrees out and it easily kept the whole first floor of my 1500 sq ft home around 71-73 degrees. Photos of the process are attached. I hope this information helps anyone that is wrestling with the whole backing plate thing or is deciding on whether or not to go with the CI1250.