The reason I personally like the 140, is that I know it works at long range as good as the 170, since we have used the 140 on elk out to over 700, and the 170 on elk out to 900, and also, if we have a shot at close range, I know the 140 holds together even with impact velocities over 3000 fps. However, we haven't shot any elk with the 170's really close, so I personally can't say how the Berger would do at high impacts. But with a shoulder joint impact of say 3100 fps with the 170, vs 3300 with the 140, I would feel better with the 140.
But if all your shots are likely to be lower velocity impacts, I really can't say anything bad about the 170 Berger, it killed quite a few elk, deer and pronghorn with authority for us as well, and was VERY accurate.