I had an "issue" with them and I got turned off. I never had a problem with the old X. People used to say it fouls the bore too much, the petals can (and did sometimes) break off and some rifles simply would not shoot them well. BUT, they did kill game quite well.
So this spring I was out bear hunting - .338 WM + 185gr TTSX.
I'll be the first to admit that I can mess up, but I can also tell you that I can shoot quite well and have been hunting for 27 years. Having said that, I hit and lost 2 bears in 3 days. The first one was ranged at 279 yards. It dropped at the shot, squirmed around, popped up and made it into the bush (5 yards).
We searched for over 2 hours with NO sign of the bear. There was not even a speck of blood anywhere - not even where it had dropped. I felt the shot was ok (broadside slightly 1/4ing away) - perhaps a touch high.
The second bear was when we were out two days later. I ranged it at 270 yards. I had a rock solid rest and all the time in the world, and given the events of the earlier hunt I was exceptionally careful. At the shot (broadside) my partner and I heard the tell-tale "thump" of the bullet impact. The bear took off and I fired again as it was 1/4ing away into the brush. Again we both clearly heard the impact.
1 1/2 hour later - no bear, no blood, nothing. As you can imagine I was quite dejected. My partner, an old timer who used to be a guide was very surprised at the events too. He asked about my ammunition - and I told him what I was using, although he doesn't put much thought into these types of things. He didn't know what a TTSX was.
So that put a bug in my mind. That is why I did the following test. I loaded up some 250gr Partitions and went to the range. The rifle was still sighted in properly, so there was no fault there. I placed a round of spruce out to 200 yards and fired a 185gr TTSX and a 250gr Partition into it.
The TTSX penetrated ~50% further, had a very small channel of destruction and opened up a very small amount - it didn't even open half-way down the cavity. The 250gr Partition had a channel of destruction at least 2x as large and mushroomed very nicely.
I prefer a behind the shoulder shot, but if it barely opened on such tough media at 200 yards, then what would it do on lungs at 270 yards?
My close friend, had just purchased a .300 Win Mag and the TSX shoots very well out of his rifle. We went out to the bear spot and looked around again. He said, "Man, you may have messed up the shot, but I have seen you shoot before, so now I am concerned".
There are numerous others who have posted similar issues.
Fortunately the vast majority of TSX and TTSX bullets seem to work very well, as evidenced by the very strong following on many forums. It seems to me that when someone posts a problem, those who have had nothing but good luck blame the shooter or some other factor.
But the fact of the matter is that some of us have had a bad experience (or two) and it doesn't take much to sour a person.
Take it how you will but I moved back to Partitions because they seem work
all the time. In fact, I just came back from a deer hunt. Three shots with my 7mm RM and 175gr Partitions gave three cleanly and quickly killed deer. I don't know if it is just bad luck or what given how many people are raving about the wonders of the TSX/TTSX.
Here is a picture of the bullets pulled from the spruce round. Note how the TTSX barely opened. Compare it to the pictures posted by others who have tested the TSX/TTSX into media. Yes, I know spruce is not flesh etc etc etc.
The way I see it, I am 100% confident in the Partition, and that means a lot to me.
YMMV