I’ll vouch for the dishwasher method personally - I’ve washed several keyboards this way and never had an issue. I never felt the need to disassemble them either.
It does generally take several days to dry completely, as you mentioned, so be sure you have a spare before doing this. If you’re in a pinch, you can lean the wet keyboard up against a box fan on high to speed up the process dramatically.
One thing I haven’t tried is washing an IR or Bluetooth keyboard, but I wouldn’t expect that to be much different in practice.