If I could have only one, and knew I was headed toward ultralight, I agree: Jordan et. al. are excellent.

By "hard core," I'm referring to the bleeding edge a few years ago, when Jordan's book first came out, not where it is today. If I remember the book right, there's a definite bias toward frameless packs, alcohol stoves, closed-cell foam, and single-wall shelters - and 12-pound base weights when "traditional" was twenty or more. Now, since ultralight has gotten the attention of mainline manufacturers, those 12-pound base weights are possible with more "traditional" gear: reasonable-size internal frame packs rarely exceed 3 pounds, double-wall solo tents like the BA Fly Creek or MSR Carbon Reflex come in at 2 pounds or so, dependable canister stoves compete with alcohol at very equal weights, and inflatable pads like the NeoAir take comfort out of the "luxury" category (but none of this stuff gets you out of the "expensive" category.)

As a guide to ultralight, Jordan's is the best out there. But Berger's approach is a little more oriented toward the beginning (and usually traditional) backpacker - which I thought the original poster was. If the OP has any taste at all for ultralight, though, Jordan's book is great.