Only "downside" I can think of with the 260 is the low options you have with factory ammo for that caliber. But if you're handloading it, you have plenty of options. Power and accuracy wise, it's just like it's other 308Win family members (243 and 7mm-08) they typically are among the most accurate calibers. A little more umph and bullet size than the 243 and little less recoil than the 308. It never really took off because I think it was surrounded by such great company (the 243 and 7mm-08) but that doesn't mean it was a bad caliber.

Good luck,
HL