RE: have 30.06 buying 300 win mag worth it?
Sound cartridge/caliber spacing is a good thing. IMHO, for most practical purposes the 30-06 and the 300WinMag are too "close" to each other to justify having both. If you have one, then don't get the other, unless you just wanna. If you are going to make a step up, then make a "worthwhile/significant" step up, e.g. 338 or 375 that way your rack of rifles will have some width and breadth to it and you will be well set to hunt a wider range of game.
Good Luck and Good Hunting,
EKM