I have the #1H in the 405, and I want to tell you that so far with my limited experience with it, I love the thing. The most powerful rifle I had up to then was a 300 WinMag, and so this one is about the same. With factory ammo, mine shoots pretty nicely. The 300 factory FP have shot all under an inch at 50 yards (5 3 shot groups.) One was as small as 5/8" at 50. Once the 100 yard range is clear, I will shoot it there. I am expecting great things, and I am now in the process of working up some loads.
Someone on another board gave me some data that could take the 405 up to 2600 fps with the 300 gr bullet. If that was the X bullet, that would give you 375 H&H performance, for sure.
I really want to try it on moose.
Long story short? The 405 is a good cartridge, with a fair amount of potential for accuracy, and development into a powerhouse.