Additional message: Today a "Roll-back" test was performed, to change the 'EXR-5s' back to a EXR-5 by simply re-installing the original OS. This worked flawless. Our conclusion is that the 3s/5s/7s upgrade to the 3/5/7 models does not cause any damage to the instrument.

Still, keep in mind: You're on your own if it causes trouble! :-)