I have one of the Basalt leveling tripods (don't have the model number handy). It's great. I don't notice the weight difference from the carbon fiber. Nice, sturdy, light, wonderful tripod, and a good value compared to the 6x models.
My only nit pick is it's a bit 'twangier' than carbon fiber. Meaning shock isn't absorbed as easily by the basalt, and the vibration of any impact on the legs reverberates through a bit more. You'll notice it when your backpack straps or cable release float around and hit the legs. Very small nit pick, and once you're set up and shooting, it's almost unnoticeable, save for maybe a very very windy day.