Just a theoretical question, if I upgraded my DHO914s from BW 125MHz to 250MHz is it possible to undo the upgrade later, and how would that be done? Reversing the change would reduce input noise and aliasing effects.
Yes. It's easy.
Either delete the license file using ADB or try ":SYST:OPT:UNINST ALL"
(I'm typing that last command from memory from DS1054Z days so it
might be wrong.
Point is: It CAN be done... I've done it several times with ADB method while I was messing around. Basic ADB use is well worth learning for hacking these 'scopes... )
adb connect 192.168.1.xxx:55555 (five fives)
adb shell ls -l /rigol/data (all the files related to model/licenses are in "/rigol/data")
adb pull /rigol/data/file.dat
adb push file.dat /rigol/data
adb shell rm /rigol/data/file.dat
In your case it would be much easier to push a DHO924's vendor.bin to your scope than to mess around generating licenses. There's one attached to the fifth post of this thread.
Remember: Pull your own vendor.bin file first and keep it safe so you can push it back and return to your original DHO914.