I have a .260 and really like it too. There isn't much diffrence between the two. Both have hard to find factory ammo, both are really good shooters, both don't kick much, and both will put a hurtn' on anything to reasonable ranges...
I shot a nice buck with my .260 last year. He was walking at about 250 yards quartering away. I sent a 140gr siera through his shoulder and out his neck. Dropped like a bag of spuds...
The reserch that a did before I had mine built showed that the 6.5mm family really performs well. They just never caught on in the US like they did in Europe and beyond. A lot of long range compititors use 6.5 due to the fact that they offer great balistic coeficents.
The best peforming bullets will be in the 115-130 gr. range, due to the fact that most non mag 6.5mm don't have a barrel with fast enough twist to stablelize the bullets.
Good luck
Ivan