Hi, I'm new, but this is a topic dear to my heart, so...

I love full suspension. I have had lots of bikes, and I am simply a faster rider on dual suspension. a good one ( read light ) will cost you an arm and a leg. but i think its really worth it. I find that when I'm climbing technical climbs the dual helps me get better traction. and men have such an advantage when the trail points down hill, full sus really helps you keep up. My last hardtail was a womens Specialized Stumpjumper. I've got a Jamis Dakar Pro, which is about 27 lbs. It's a few years old. I just got my new bike, a custom DEAN baja. It's titanium, and I don't have it built yet (not in a huge rush being 9 months pregnant) but it should be considerably lighter.

I would say that if you have a hardtail, keep it and buy full suspension and ride the appropriate bike for the trails. but i garauntee the hard tail will gather dust.