From the article:
To be sure there are still some lingering uncertainties. Some recent data indicates that tropical upper tropopsheric water vapour does not quite keep up with constant relative humidity (Minschwaner and Dessler, 2004) (though they still found that the feedback was positive). Moist convection schemes in models are constantly being refined, and it's possible that newer schemes will change things . However, given the Pinatubo results, the models are probably getting the broader picture reasonably correct.
First off ...what is relative humidity telling you? What you really need is the specific humidity if you really are concerned about the equilibrium temperature. Second...the sentence on the computer model is really telling isn't it. Their projections are wrong...so they tweak them some more. Just like the IPCC has been downgrading all of their projections to fit their data. Given enough time they will see that the sky was not falling after all.
Water...unlike CO2 and the other supposed greenhouse gases absorbs across the entire spectrum of the infrared. I'm not sure why this is so hard to understand for some.
As regards water vapor as a forcer, it has been tested, by the Pinatubo data, as the article notes "the models are probably getting the broader picture reasonably correct".
IMO, the way this is heading is pretty clear: 5 years or a decade from now the more scientifically literate skeptics here will be saying 'Well, in the mid 00s, we still had reason to be skeptical, and after all things didn't turn out to be as dire as suggested by the more pessimistic models."