I've only had my BG42 Military for about a week, so I have no long-term perspective. My other Military is an older 440V version. Most recent S30V blade is a Manix.
Initially, my impression is that the most apparent difference between BG42 and S30V is a striking difference in ease of sharpening, in favor of the BG42 blade. I think we've all come to expect a harder blade (Spyderco BG42 advertised as 61 hardness) to be difficult to sharpen, but that's not the case with my BG42 Military.
I don't do quantitative measurements of edge-holding, but so far edge-holding seems about equal (between Manix S30V and BG42 Millie with same edge profile).
One difference I've noticed, regarding touch-up resharpening of the edge bevels:
- The S30V blade responds well to CrO-loaded strop for touch-ups.
- The BG42 blade doesn't respond well to stropping for touch-ups (edge-rounding of the micro-bevels).
- Best BG42 touch-up sharpening results with Spyderco DoubleStuff ceramic hone.
That's about all I have to offer.