I don't know if anyone else chambers for 338-378, but don't let the wby naysayers stop you from getting one if that is what you really want. If you get one and it is not as accurate as you want, send it to one of the smiths on this site. Nine lugs on the bolt seem to be the main thing everyone has issue with and yes they can a problem but they can generally be made to work together just fine.
My 338-378 was converted into a 338 Kahn (a wildcat that mainly just gets rid of the compound radiuses on the shoulder) It shot quite well as a factory rifle, nothing spectacular but good enough for 500 or so. I also have a wby .416 that shoots very well.
The 338-378 is hard to beat for raw power in a .338 cal. The .338 Lapua is the next best thing in a factory cartridge. The .338 EDGE is pretty hot but is a wildcat that would require a custom rifle
and fireforming your brass.
I am currently having a .338 Lapua built by Kirby Allen (fiftydriver) The Lapua is a very accurate cartridge, you can buy excellent brass, and it is a pretty close second to the 338-378.
Last, on your post about scopes you asked about swarovski scopes. I have two that I would be willing to part with a 6x24 and 4x16 with tds reticals. They are great scopes and I have no complaints about them. I will admit however that I am replacing them with Nightforce scopes. The primary reason is the target turrets on the NF. I got my first NF a few months ago and started dialing up my elevation rather using multi line reticals.......I'll never go back. My reccomendation for scopes, Nightforce. But the swaros are quality optics as well. If you are interested drop me private e-mail and we will talk $$