I've used all three major brands of monos on big game, and also shot them into test media. While there can be small difference seen in media tests, I have yet to be able to tell any difference on game. All three open into four "petals," and usually retain all four, though sometimes lose anywhere from one to four petals, particularly if they hit bone.
The exception would be the LRX (Long Range X-Bullet) which has the petals annealed to enable the bullets to open up at lower velocities. This sometimes results in losing petals at closer ranges.
But also have never been able to tell much (if any) difference how various monos kill game based on how many petals they lose or retain. In fact, some other monos (such as the Cutting Edge Raptor) are designed to consistently lose their petals, which supposedly results in more damage around the primary wound channel. But there are many variables in both animal reaction and bullet placement.
The other factor is that (as noted above) TSXs, E-Tips and GMXs all tend to lose petals when they hit heavy bone. This often results in more damage, despite the petal loss, from bone fragments. A good example would be a big cow elk my wife killed a couple years ago with a 130-grain TTSX from a .308 Winchester. The cow was quartering toward us at around 250 yards, and the bullet landed just above the big joint of the left shoulder. The elk staggered 20-25 yards and fell over, obviously done for from the moment the bullet landed. We found the bullet, minus all four petals, under the hide over the right ribs, only retaining around 60% of its weight, due to the loss of all its petals.
Saw the same sort of thing several times with the discontinued Fail Safe bullet, which also opened into four petals. Even if all the petals broke off, the animal died quickly--usually quicker than if the bullet didn't hit major bone.
