I was under the impression that the Sierra Denali is only ~200-250# heavier than the SS. My SS specs said like 5300# (2003 AWD Victory Red). I was impressed given that this is a crew cab compared to my extended cab, I think the using the aluminum block definately helps.
I actually just ordered new SD 2 weeks ago, black on black.... can't wait!
Really, I love my SS, but just ran out of warranty so I started looking around... Didn't even know about the Denali's, always thought they were just shinier. Dealer sold it to me for invoice and gave me a decent trade in so I'm gonna have the sweetest new truck and my payment goes from $525 to $500/mo, it was kind of a no brainer.
Besides, given the fact that my new SD will be MINE, means it's definately faster than yer VHO!