Seems to me the standard 338Win is a better all around bet.
The 375 is mostly successful because the 375H&H wont fit in the Ruger action....Giving it a reason to exist.
I've had mine since they first came out and its a nice round.
Originally advertised to be the equal of the 338 WM, the factory loads probably were, but my handloads for it are closer to 338-06 velocities.
Case life is excellent and the rifle feeds and handles the cartridge very well.
As for popularity, it likely won't achieve the sales numbers that Ruger had anticipated, however it is still a fine hunting round.
What is the water capacity of the 338RCM???
CC