A couple of quick things. I recently swapped from the HD Heated Grips to the Heat Demons when I swapped to the HD Pull Back bars.
Regarding performance, the Heat Demons do not get as quite as hot, but based on the reports, and the dismal life I saw on my 3 sets of HD's, I fully suspect the Heat Demans will last much longer. The reason the Heat Demons aren't as hot is the grid is rolled up inside the bars, where the HD grid is inside the grip itself. Not that there's a big difference but the stockers could get hot enough that they were uncomfortable to hold with bare hands, whereas the Heat Demons don't get quite that hot. That very well might be the primary reason why the Harley's grips burn out so often?
Anyway, regarding the install, be VERY careful with the wires attached to the grid, especially when fishing the internal harnesses. It is very easy to pull these wires off the solder joints if the harness fishing snags. Just watch it closely.
Lastly, after an indepth discussion with the folks at Heat Demons regarding this reaming matter, they suggested AGAINST this! The grids are flexible and plenty capable of fitting bars a bit below .875". If close, don't bother reaming. To confirm the need, just make sure the grid doesn't overlap itself when inserting. If it doesn't, you're good to go. Call them and confirm this.