It has been my experience that with a .270, 30-30 and .308, standard cup-and-core bullets have performed great on deer out to 150 yards or so. It has also been my experience that the TSX (and I would assume but have not tried the TTSX) bullet shines when used in what may traditionally be considered a "light" caliber for deer going really fast. I never thought the .223 was a deer round until recently. Now, after seeing 250+ pound deer drop like lightning hit them, I am a believer.

I still hunt with my .270, 30-30, and .308, but I don't have a problem with the .223 if someone who's recoil shy wants to shoot with it.

I just didn't see any difference in performance with the "real" calibers to justify the expense.

YMMV