YOTEBOY,
I have used RL-19 for quite a few years in my standard 7 mag. The loads developed were worked up in the 60 - 75 degree temp range. They have shot fine out to 500yds, down to the 30'ish degree range, with no notable issues. On the other hand these same loads will provide some sticky bolt issues with temps above 80 - 85 degrees. As was mentioned in the post on temp sensitivity, something about that 80 degree mark.
On the other side of this coin, when I have used a couple of the RL powders in mid sized cases, like those in the '06 size, I have found that if using close to or a compressed charge that the drop off was very notable. One in particular was for a 165gr load in 30-06 using RL-22 which when worked up in 80 degree weather, shot similar to a gallery load once the temp dropped below 40. I also had a similar issue with RL-19 and some 162's in my .280. Same issue, worked up a great load in 80+ degree weather, then when shooting in the mid 30's - 40 degrees, the bottom dropped out of them, and I got 4-6" differences in drop at 200yds. Bear in mind that both of these were close to full case loads and in smaller cases than you will be using.
Your tepms will be on the opposite end of the spectrun from ours down here in the balmy south. I would not hesitate to give it a try as it has and does produce some awesome groups, and great velocities in those bigger cases.
Good luck, and post up what you find with yours.