I have shot both styles and they both can work very very well.
See the 6mmbr.com link in my sigline for my other projects.
For the Savage, there is no benefit either way. The only advantage with a shoulder headspaced barrel is the ability to use a larger profile. This can be useful if shooting a larger cartridge in F class where you barrel gets super hot.
If going barrel nut headspace, you can install yourself and can change barrels whenever you want. Saves quite a bit in the install labour over a few barrels.
http://www.canadiangunnutz.com/forum/showthread.php?t=654151
Scroll to the videos on the bottom of the 1st post and you can see what some prefit Shilens are doing on my FTR rifles.
Unfortunately, I can't blame the equipment anymore....
Jerry