Either rifle is a fine choice.
BOSS works, but if you don't know how to use it it can be an exercise in frustration. All it really does is tune barrel harmonics to a given load, if you change loads (or maybe even lots of the same ammo) you may need to adjust the BOSS.
For deer, there is no need for the 270 WSM, so go with the venerable 270 Win.
Jimro
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