I had a light hardtail, now I have a slightly less light XC-biased FS bike (Scalpel). I much prefer the latter, the traction and control with the rear wheel is much better. Places where the rear end of the hardtail would feel skittish, feels much nicer on the FS bike.
It also inspires confidence, having that extra control.. my hardtail was a chuckable little thing, despite the FS being a little heavier it feels every bit as agile and then some.
And the rear shock can always be locked out to emulate a hardtail when you really need it.. it's not quite as direct a feeling as a 'true' hardtail but it's close.