I didn't answer earlier because I don't know how the 15 performs, but I fear it will be the same problem as other scanners. My 396 won't do Red Deer, and I suspect the 15 (and the 996, which I believe is based on the same code/technology) won't track it.
The problem is that the system sees the trunk channels as 866.05, 866.55, 867.05, etc. The system knows the channels just fine because of the design of the programming that the radios use to communicate, which knows that for this particular system, channel 604 (or whatever) is 866.05, etc. However, to a normal trunk system, and to the Uniden scanners (at least the ones of recent times), that channel is actually 866.0625 - which is 0.0125 higher. The same goes for the entire 800MHz band.
It would be nice to know if a RS/GRE scanner could track the system. Or if a firmware update or future Uniden machine will work. I 'm pretty sure that UPMan (the Uniden product manager, who is a member of this site) is aware of the Red Deer system, because IIRC he participated in the thread a while back when we discovered this issue.
For now, I'm sorry to say that I don't think you're going to have much luck tracking Red Deer, unless you find a way to get around this channel/frequency mismatching.
