Is it "OK" to install Ubuntu on one laptop and put the SSD into another?

Solution 1:

You can, I have done it myself without any issues.

Though as the comment says, you need to remove the 3rd party drivers before moving the SSD to the other.

Solution 2:

I've done it myself as well, it is completely possible however there could be a few settings off (i.e. Screen resolution). If the new hardware/laptop requires new third party drivers Ubuntu will automatically call that our for you or you can just manually installed them to get better performance.

Solution 3:

Yeah, it works extremely well. One thing I came across doing this, was that my network card was not auto detected anymore.

I found out that a custom rule targeting my specific network card had been added to /etc/udev/rules.d/70-persistent-net.rules by the ubuntu installer to make sure eth0 would always be eth0 even if another card was added. I deleted the file and on next boot everything was well. I don't remember the Ubuntu version, so YMMV. But in case you run into trouble, /etc/udev/rules.d/ might be the place to look.