Yeah, I know this thread is old, but I couldn't resist. It was fun to watch.
I have a 2019 Silverado, with the 4.3l. Compared to my 2002, with the 5.3l, it's not a slug. Then again we're talking a 17 year difference. The HP and Torque rating are pretty much the same between my two trucks. I'm willing to bet if you were happy with the 5.3l in an early 2000s Silverado, you'd be fine with the recent 4.3l.
The only thing I really noticed is that the idle on the 4.3 is rougher than the 5.3. The 2002 was smoooooooooooth, even when it has over 200k miles on it.