I would not discourage a shooter from buying another barrel for their Encore. Lord knows I have a ton of them. However there is no difference between the 30-06, 270, and 7-08 out to 300 or 400 yards. Unless someone wants to argue about an inch or two. The 30-06 with a comparable bullet(weight wise) will easily do the job.

Personally I prefer the 30-06 with the 165 grain bullet for distances past 300 yards over the other cartridges listed. The heavier bullet is better(IMO) downrange. Tom.