Yeah that's true. I guess i didn't think of it as an "upgrade" but it kinda is.
The quality of microswitches varies and some people do find that the Z switch isn't within microns accurate enough for the job.
I went to optical and then to hall effect Z endstops.
You can find the mounts and interrupters in my 'things' as i remixed them. I'm not sure with a clear conscience i can recommend my hall effect endstop because it's just a hack to see if i could use an aliexpress hall effect sensor module for arduino hacking that costs less than $1 as an endstop and it totally works and so far seems reliable but wtf do i know?
The optical endstop uses commodity reprap stuff that is tried and true.
If your build plate droops when the Z motors aren't powered, there's probably a combination of pulleys and closed-loop belt that fits Just Right on the 500 size printer, the way there is on the 330mm printer. But i dunno what it is.