Hm...

Disclaimer: Not a mountain biker (too clumsy).

Will this be a "forever" bike, or do you see yourself upgrading to a new bike in the future? How much more is the Advanced, and will that eat any upgrade budget? With Giant's numbering system, yes, the Lust 1 will have better components and wheels off the shelf. The carbon frame is probably going to be a bit lighter, but given that they have to beef up the frames a lot for mountain bikes, I'm not sure that there will be any meaningful weight savings, especially when you add in the weight of the heavier components. (You might ask your LBS to see if they can get that information out of the company. They don't publish that.) Would you notice the ride difference?

If you see yourself upgrading to another bike in the future, I'm not sure the carbon frame is worth it. However, if you think this might be a forever-bike, then I'd more strongly consider the carbon frame and make changes when you can afford it/as necessary. (As it is, I'm a little bit leery of carbon MTB frames, but as far as I can tell it's not a huge issue for the average user.)