If anything is underrated, it's 6.5x55 Swede. Americans have scoffed at this cartridge for decades. Hell, we still can't come to terms with it. We have to go off and have a "sister" cartridge to it...the .260Rem.
The 6.5x55SE is indeed a great cartridge. the .260 has another advantage, though... it prevents lawsuits. There are a lot of old guns chambered in 6.5x55SE that can't handle modern pressures. Ammo makers in the USA can't load hot ammo because someone would have their gun blow up and then sue the ammo maker... unlike in Europe where they load them hot and then tell users that if they use hot ammo and their gun blows up, it's the user's fault for being stupid. So... the .260 lets USA ammo makers have a modern 6.5. I'm also a fan of the .260 (and own one). Plus... .260 brass can be resized from a host of the most common cartridges in the world (.243Win, .308Win, 7mm-08) and the 6.5x55SE is it's own.