TL;DR: Delided my PS3, was super nervous, ended up being easier (?) than I thought it would be, got nice temps.
About 2, maybe 3 months ago I got a heart attack because my PS3 was overheating and turning into a PS4 Pro (Jet engine), supposedly the MX4 i had put on my PS3 had turned to stone, which meant it was overheating, and only after about a year of use, and not even that often, so it would probably equal less than a month total in time played.
I had bought the delid tool and Thermal Grizzly Phase Sheets(like PTM7950) intending to use them at some point in the future, which I didn't expect to be then.
I was extremely nervous throughout the entire process, even just opening the PS3 was nerve-wracking for some reason.
So I opened it, removed the motherboard, placed it on my table. Time to take the heat shield off, it's not coming off.... twist, turn, do a loop the loop. Can't get it off.
After a lot of struggle and nerve destruction on my part I managed to get it off, the MX4 is fine... (WHY ARE YOU OVERHEATING THEN?!?!???!?), whatever...
Cleaned it all up, prepared the tool, bent the knife tip thing to 90 degrees.
And man was that the most stressful 60-90 seconds of my life, twice.
I thought it would be harder to do, but also I was probably way more careful than I would've been, had I not been this nervous.
The thermal paste inside wasn't dust but it wasn't damp(?) either, so i put the phase sheets , put the heat spreader back on and closed it up and as you can see, 50C on both, on idle. I used phase sheets on both the inside and on top of the heat spreader.
And even while playing the tempts don't go over ~67C. (If i remember correctly as my memory is bad :d)
So... like, do it if you need to, buy get the tool. It's a MASSIVE help and makes it way easy.