Do I "need" a controlled expansion bullet here? I am considering a cow hunt.
Do you need steel-belted radials when plain polyester cords sufficed for millions of people for many years? Do you need 4x4 capability when 2-wheel drive is good enough the vast majority of the time?
A bullet that fails to expand, as Barnes XLC's appear to have done for me, is one extreme. One unfortunate antelope took two to the chest yet refused to die. The tipped TTSX and older MRX seem to have solved that problem and have provided more straight down DRT results than not for those in my hunting parties.
The other extreme is bullets that sometimes come completely apart and may not penetrate well as a result.
In-between you have controlled expansion bullets. The Partition has been around forever and still works great. A-Frames and Trophy Bonded are a step up IMHO. It took me 20 years to recover a Grand Slam and when I did it had destroyed both shoulders on a 5x5 bull elk. Tipped monos like the Barnes TTSX expand reliably but hold together and penetrate very well - we've yet to recover one.
The cost difference between the various types is pretty low when compared to the total cost of an elk hunt, even for resident hunters like me. Practice with cheap ammo and hunt with the controlled expansion bullets. At worst they will cost you a little extra but they may make the difference between harvesting an elk or losing it.
