I also have a 300 RUM and love it, but if I had to do it all over again, I'd get the 300 Win Mag. Ammo is less expensive, whether you buy it or reload, and the recoil is significantly less. It will also kill an elk at 1,000+ yards, which is more than I care to shoot at, so no need for the extra velocity from the RUM. Regardless of whether you reload or not, ammo is significantly more expensive, but you'll want to reload if you shoot the RUM as finding ammo is not easy.
With that being said, if I were to get another 300 RUM, I'd buy a new one in a Remington 700 platform, preferably the SPS since it's less expensive. Throw a Bell & Carlson Alaskan stock on it, bed it and float it, and throw a Timney trigger in there and you should have a shooter. I say buy new because the barrel life isn't that long on a 300 RUM, so unless you are getting something that has minimal rounds in it, I'd go that route.
If you reload, I can highly recommend the 230 grain Berger Hybrids. They have performed unbelievably for me through the years at a variety of distances and on a variety of animals.