My launch DS4's thumbsticks were still in one piece and no falling apart, but the rough-texture grip has long since been rubbed away resulting in a complete lack of grip that caused my thumbs to slip-n-slide all over the place whenever I held the sticks in any direction for longer than a second or two.
So I ordered
the aluminum metal dark grey sticks and went to work.
Holy shit, replacing the sticks is a pain in the ass on the DS4. Popping out the back panel and unscrewing the extremely tight screws was pretty frustrating. Even more frustrating is the fact that the back panel is held together further by annoying clamps from the inside, so you have to REALLY pull the controller apart to get them off and there's a good chance you'll break off the tabs.
Most annoying are the triggers. The plastic of the back panel wraps around between the shoulder buttons and the triggers, so the triggers themselves have the back panel wrap around them entirely. If you yank out the back panel from behind the triggers will pop off and the REALLY small, REALLY flimsy spring that makes the triggers...well...springy, will fly off all over the place if you're not careful. This basically means I spent like 20 minutes trying to "unrwap" the triggers from the backpanel while simultaneously not pulling that hard so as to not pop the triggers off. I still managed to pop the left trigger despite my best efforts. A fifth super-tight screw holds the main controller PCB in place BUT WAIT! You can't quite pull it off yet because the touchpad tape cable and the LED light tape cables are in the way. You absolutely have to remove the touchpad tape cable to get to the analog sticks. You can choose to keep the light bar LED tape cable in place, but it means you can't fully separate the back panel from the front at any point in time. I opted to do that and it was annoying, but I wanted to remove the least number of cables possible.
I was cursing at Sony throughout the entire replacement. If they were going to half-ass the original thumbsticks so much, the least they could've done is make the sticks easy to replace. But instead they require that you disassemble the entire controller just to get to the sticks, and the really weird angle through which the back panel pops into the front one combined with the panel wrapping around the triggers made for some really annoying shit.
But the replacement sticks themselves are awesome. I love the heavier feeling to it, and I love the grippy nature. I'm also happy that they're aluminum metal, meaning there's no way the grip is going to "fade" the way the shitty plastic grip faded after just over a year of pretty light use.
I honestly don't know why Sony/MS/Nintendo have never tried metal thumbsticks. IMO they're clearly superior.