RE: have 30.06 buying 300 win mag worth it?
If you are wishing your 06 had a little more, you could look at reaming out the chamber, have an 06 Ackley Improved. Of course you will then get the satisfaction of having your friends with the 300 WM work up a reload for you, and they will wonder how that measly 06 can shoot flatter than their magnums...
The 06 improved shines the most with the heavier bullet weights. Reaming and die set should be around $200.
Then you will still have the benefit of holding a rifle you are familiar with, mostly. If you ever find yourself without your handloads, you can still buy and shoot factory 06 ammo.
But, as has been said, there is nothing wrong with another rifle in the stable either.