My first thought was "What does need have to do with it?"
If you want one, you want one, and until you have one and experience it first hand, you won't be able to answer the question for yourself...
And the fact that it carries more velocity and energy at longer distance (400 yards vs 300 yards) is comforting when an opportunity presents itself on a larger animal.
I like the 6.5s...always have... having spent more time with the 6.5 Swede than any other centerfire cartridge. Now have a LH Sako 85 Hunter that shoot better than 1/2" groups with factory ammo. Have a good supply of 140 gr AccuBonds to work up a load with.
Had one of the first 6.5CM is a Ruger Hawkeye when first introduced...and now have a Browning X Bolt All Weather rebarreled to 6.5CM because they decided not to produce it in LH. Shoots 1/2" groups or better with factory ammo (Hornady ELD-X and Federal Terminal Ascent). Performed very well on my red stag @ 296 yards, and fallow buck @ 267 yards and Arapawa rams @ 120 and 122 yards for the wife. She likes it so much, she bought her own LH Hunter in 6.5 Cm for our trip to Africa next year. Also have a good supply of 130 gr AccuBonds to work up a load with.
I am also interested in the 6.5 PRC, and am just waiting to take a LH X Bolt Hunter in 270 WSM to swap barrels with a 24" Wilson carbon fibre 6.5 PRC barrel. I had a 6.5x284 Norma, but am going PRC as I believe it will have better barrel life to get the same level of performance. Will see if it prefers 130 or 140 gr bullets. Although would prefer the 140s if larger game encountered, and mtn goats are tougher than mtn sheep. Some species just require more velocity/energy to immediately impress them.
I also like the 7mm's, and have a STW for more open terrain hunting if I need more reach and power (elk) that will shoot 1" groups @ 300 yards.
I like what I am reading about on the 7mm PRC...just not sure I will get one at this time as I still want to play more in the 6.5 arena.