"I don't know what a Glock is but it sounds vaguely obscene. And why would you need to circumcise it anyway?"
There's nothing civil about this war.
The only slide cut I would do in any gun is to fit an RMR!
SIG, not a Glock but the same rule applies.
It's probably worth mentioning where all these slide lightening cuts came from. Open guns. Specifically 5 inch government slides, with .355 caliber bull barrels and compensators. That's a lot of reciprocating mass. You add the comp slowing the slide down and suddenly you need a very light recoil spring to get the thing to function. Cut slide mass and you can up the spring weight and get more reliable feeding. Even with all that I'm running a 9 pound progressive on mine.
A lighter slide will make the gun feel snappier. If you're running a 5 inch government slide and bull barrel in a limited gun with USPSA normal loads (which are reduced a bit from duty .40) some might want that. There's also plenty of folks shooting the STI Edge, which are actually designed to be as heavy as possible.
In a 9mm Glock for 3gun I could see it. But for all that money, I'd just buy a 2011.
Shooting duty/defense ammo? Stupid.
Being a noob, I told myself, "learn to shoot, get the basics sorted to better have a base of knowledge to be able to tell the difference between what are basically subtle differences". (I regret filing the finger bumps off the front strap for that reason, I got impatient and forgot what I'd told myself).
Having watched Frank Proctor's videos on slide manipulation I've been using grip tape in lieu of front serrations on my G17. I like the efficiency of movement they offer and the tape is just in front of the ejection port, I don't see any advantage their being any further forward but its more than likely one of those "you don't know what you don't know" things. I don't really get the fears people have for getting your hands too close to the muzzle, if you're manipulating the slide, your trigger finger shouldn't be anywhere near the trigger.
I chose to buy a pistol that doesn't have front serrations, at the time of buying I didn't have the experience I do now. If Glock offered a version of Perfection (tm) with front serrations, I'd go for it. If I choose to further ignore my original plan and have the slide modified, I'd go for the minimalist cut and aim to take as little weight from the slide as possible.
Grip tape works, it looks fugly and the cool guys will laugh, but hey, who cares?
As for making the slide lighter? Why? If Mr_White, SLG and umpteen others can shoot sub .25 splits with a regular slide, it's not the slide needs improving to shoot faster.
Framework, yes I like to do it on a Glock, just like I prefer to work a 1911 frame. When I finally became more open minded about polymer framed pistols and got into Glocks, I thought why not fix what Glock got wrong from the factory? This was early on and while I knew of others just getting into more mainstream "Glock smithing", I thought it was a natural progression to carry over into a Glock since I was doing similar work already. As it turns out, polymer pistols take well to the work and the Glock while very shootable out of the box, is so easily custom fit to an individual if they are having issues.
I don't do any slide work as it is just not important enough on the Glock for me to want to add them aftermarket but I would welcome factory cuts. My Glock work visually is pretty tame compared to others and while I don't really care too much about the visual "bling" aspect, I do like the benefit of fitting the Glock to my hand.
Forward serrations leave my "brand" when somebody bumps his head on my pistol.
The other thing to add to this is a 1911/2011 gunsmith can control the rearward motion/speed of the slide by altering the angle between the firing pin stop and hammer and/or adjusting the mainspring weight. This can allow you to make a slide much lighter without necessarily increasing the speed of rearward slide movement. You can then adjust your recoil spring weight on a lighter slide to slow down the forward motion of the slide as well and not affect the timing of the gun.
There is nothing that can slow down the rearward motion or unlocking of the slide on a Glock except a stronger recoil spring, but then that will speed up the forward motion of the slide (even more so on a lighter slide). Bad things happen when you alter the timing on a Glock (or any similar striker fired pistol), and you will start to have issues with the slide outrunning the magazine springs.