I've been using both of them for years and years. Amazing.
You can get cable replacement kits for the MX518/G400/G400s for $9 from eBay that includes new feet and a USB cable. So I'm really not worried about longevity.
P.S. You should take the mouse apart and clean it probably at least once per year. I cleaned my MX518 after about 5 years when the scroll stopped working consistently. I was shocked how much hair was on the inside, blocking the scroll sensor.
I find I need to clean my scroll wheel maybe twice a year. It gets more stuck with gunk over time, and it becomes harder and harder to scroll.
but both are discontinued
It sounds like a squeaky wheel or a squealing (real, animal) mouse.
Other mice do not cause this problem. I mask it out with noise canceling headphones but I’d love a nice mouse that doesn’t cause this behavior. I’ve tried ferrite loops but they do nothing.
Other than a cable replacement and a switch cleaning, both of those original G5’s are still perfectly operational after over a decade of regular use.
Ironically I switched to the MX series (multiple mx2 and mx2s, home/work) and I absolutely love them apart from the problems I used to have where they'd stutter on every OSX machine I used them on. I haven't had that problem in maybe a year, though. Logitech or OSX BT update maybe.
I can't go back to a non MX scroll wheel. I love it.
I tried the open source drivers on my MS Surface but I never got them to work.
The cable finally wore out on my old Logitech G5 and I was able to order a replacement for a few dollars. I also had to replace the skids since they covered the screw holes. All it took was a screwdriver and five minutes.
The Logitech Trackman Marble is my go-to now, but its nowhere near the legendary FX.
https://www.amazon.com.au/ELECOM-M-DT2URBK-Trackball-Finger-...
Wireless, uses AA batteries. Not as expensive as the latest Logitech trackball.
Its not anywhere close.