Hello Aaron Nietfeld,
Since I have no interest in rifles with interchangeable barrels, I should probably keep my big mouth shut (except for doubles and hinge frame single shots - those designs beg for extra barrels in other calibers/gauges).
However, being also a hyper active motor mouth, I cannot help but to open my big mouth sometimes.
Of the two rifles you are considering, I would select the Mauser M03 (too bad it is not a Mauser M98).
All the straight-pull rifles in the world have always looked as ugly as home made soap to me.
More importantly, some have a reputation of failing in the worst way, resulting in severe injury or death to the shooter.
I feel this is due to the fact that they have so many intricate and complicated looking little moving parts that mathematically, the odds of something breaking or failing to go where it belongs are increased, compared to most of the more simple turn bolt designs (an exception is the Sauer turnbolt design, those make me nervous as well - too many moving parts).
The Blaser R8 might be one of these death traps, not sure but I'd personally never want to fire one, even if this particular model has never failed anyone else (Murphy's Law seems to be my constant companion).
Blah, blah, etc., etc., get the Mauser,
Velo Dog.