Any of the varmint bullets will open up too quick and/or fragment and limit penetration. A good head shot will generally be effective with these bullets. But a shoulder or body shot will lack penetration. The 125's are a little slower and heavier, and penetrate very well.
Also, the 150 grain BT bullets will go clean through big pigs. I have had pass throughs with the 150 BT, one on a very large hog running from about 40-50 yards right behind the shoulder. Exit was about dime size, so I don't think they are expanding as good as the 125's are.
From my customer feedback and my personal experience, the 125's offer the best overall performance for the blk out.