I didn't have to play around with seating stems for 105 or 108 Bergers, or 107 Sierra but I also don't go crazy with neck tension.
Only way to know is in your own context. They offer more than one stem, but I didn't find the Wilson stuff to be very fussy at all. YMMV
Using Wilson dasher seater for BR you will be fine. The .80 difference keeps the BR shoulder low enough to not sick the BR shoulder in the dasher die. Been doing this for yearsI have a Wilson dasher seater, how well would it work for a straight br w 108 bt?
ty Don