Well, shaving 5 lbs from a bike might be a bit counterproductive. Bikes are made for a certain suite of components. Does it make sense to run really light and expensive components like ultra high end wheels and tires and have dirt cheap, clunky brakes? Why stick $1000 of wheels on a $600 bike?
I think if you want to go for a light ride, just go and get a whole new bike. Use your old ride for a back up and a beater (rain, bad roads, nasty conditions).
I would never spend $1000 on wheels
I'm not too worried about weight, like I said before, I don't really think my bike is all that heavy. I was just surprised when I found something where somebody saved 2-3 lbs by upgrading components. I'm not looking to spend much if anything on my current bike but still having the debate that I could sell my bike & buy a new one with that money + another 4-500 or I could take that 4-500 and upgrade a few things on my current bike & be plenty happy with the total package.
On my list:
CF Fork (more to absorb some road vibrations than weight savings)
Compact double crank (I'm currently running SORA so if I stay with that, I could get a FD for $30, a shifter for $50, & crank for another $50)
There really isnt much else that I want to change on my bike but if I can upgrade the parts that I want & save little bit of weight, why not?