Coreopsis 'Moonbeam' short lived?

I've been read that Coreopsis 'Moonbeam' is often short lived (2yrs) because it flowers so profusely it wears itself out. Has anyone experienced this? I've never had any success growing coreopsis from cuttings (this cultivar said to be sterile from seed) so I'd love to hear if anyone has any tips other than normal propagation practice. I'm gardening in S.E.Scotland so my cuttings need to survive in the house (unheated room usuall 12-14 degrees) or the coldframe. Thanks