Haha cool to get some feedback, buddies.
Well, it depends on your style, Rock god. Of course I don't believe all style require warm-up. But if you go for more technical stuff (not necessarily "big metal or shred cliché") like some jazz, country or fusion... you need to warm-up. It's safer. Especially if you're going to go for the whole night. And to me it's mostly the right hand I found out. And sometimes warming-up might just be getting the feel of the inner beat. Just getting into it. Or improvising slowly on some pop/jazz standards (All of me, Sunny, Isn't she lovely, I'll see you in my dreams...)
That Petrucci stretching never made sense to me. First of all, because like in any sport, stretching is used to get the blood flowing through the muscles to carry away all the toxins resulting from the effort. It's after the practice that you should be stretching. If you have sore muscles from sickness or previous practice, I understand. But in any other case, I don't see much sense in that.
The "Dimebag warm-up" is cool but pretty extreme. I myself can't do it. And I think that I should have better explained that warm-up can be a good opportunity to improve your melodic playing: following the chords, not just playing scales or "visual exercices". Because when improvising or writing, you usually come to a point where you vomit some stuff you learnt earlier. And those Dimebag don't make sense to me.
Warm-up is simply a too good opportunity to develop melodic awareness at slow speed. It's a great practice for the ear and unlocking the fretboard overview (CAGED system). Also, like I said, it's a good moment to have fun, just getting in the mood, listening to how I feel and what I feel playing or writing.
Hence I'd say warming-up is a pretty important part of my dayly work-out. It's like preliminary for sex. If you swap them, it'll take longer to get to the point where you wanna go. On short and long term.
Just my 2 cents anyway.