This coming for a weatherby guy, I would pass. The threat response is a nice system, but with 1850 and your currrent setup I could have a much nicer Custom than any weatherby off the shelf.
If you need more power than the 338 RUM then step up to the 338 Edge. The 338-378 will be about 150-200 FPS faster, but how much do you really need?
For a grand, you could send your RUM off to one of the smiths on this sight, have a custom barrel chambered in anything you want, and I promise it will out shoot that weatherby! Heck, 1850 and a 1.5moa guarantee, you can do better.
I shoot a custom built of a weather MKV action. I have shot a weatherby since I was 14 when I bought myself my first hunting gun. I just think they are getting a little over priced when I can get a custom built for the same or less money!