Don't be caught up in all the latest wizbang offerings from firearms manufactuors. They are in the business to sell thier product.
IMHO you have to look at the factory offerings to compare rounds. The 300 Win Mag and 300 Weatherby have been around along time now. With todays bullets and powder they are still good choices. I personally limit my shots to 300yards for animals larger than deer and 400 yards for deer sized animals. Those are ranges I know that I can make good clean one shot kills under hunting conditions. Both the Win Mag and Weatherby have fine repitations in the field and on the range. Free, Schmee don't let anyone put the thought in you mind the 300 weatherby isn't a very acurate round.
All that being said I would have to say the 300 WSM would be of interest if I was in the market for a new 300 round. If you handload you have to look what goes in (powder amount) and what comes out (recoil and velocity) When you stuff all that powder into a RUM it's going to go faster, it had better. But the queston should be how much powder does one use to make all rounds equal say for the sake of argument 3100 fps and you have a 3200 fps RUM that uses 10 grs or more ( alot of powder)to gain 100 feet. That's the dirty little secret handloaders fail to tell when they post.