MY 6mm has never, ever, let me down but when a big buck pokes his head out down range I have thought I would feel better with more than 100 grains heading his way. In truth, that is about the only real difference I see. Deer would likely be just as dead either way but......I am finding the 260 to be the perfect balance of power, low recoil, accuracy and size for whitetails. With a 260 you can use 90 to160 grain bullets. 120 soft points and bt's, 125 partitions, 129interlocks and 140 gamekings are the most common choices and if we are talking deer size game I find that a perfect match. I am with you in that I don't see the point of going 100grain in 25 caliber - though newer bullets are fine for it. I bought my 260 to be between my 6mm and 270 but now find it overshadowing both. Mine shoots 140 Sierra's remarkably well and the results are fabulous. The gameking has a reputation for opening fast ( some say too fast and have trouble keeping its core) but the high sectional density and the slightly modest speed at which the 260 pushes them is a great recipe for maximizing their potential. If 250+ yards starts becoming the norm then, although many will disagree, I would look to a flatter round and grab my 270, for all else -Get a 260 and you will fall in love with it.