Well I personally can't explain the suspended time trials, but I'm guessing if you are going to do a full unlock that this isn't going to be an issue.
I have a DS2102, all I did was upgrade to the new 00.02.01.00.03 firmware via the boot upgrade (ie. USB Key, Power, Help Key), not the process where the scope sees the newer firmware
on the USB key and asks if you want to upgrade. Made sure to reset to factory settings during first boot with newer firmware using the Left F6 key (repetitively pushing during boot). Then used the CAN & 300Mhz key codes generated by key generator (rigLOL website, you can link from here:
http://rigol.avotronics.co.uk/mirrors/riglol/) to preserve the existing codes I already had (as with your 56M).
To generate a key, simply add your serial number (for your scope) to the text box called serial: DS12345678901, then add the option you want a key for, let's say DSHH for all options, leave the private key box empty, then hit the GENERATE key - Use this key in the Options Setup Screen on the scope.
I 'assume' you can use the DSHH code with your Scopes serial and be up and running with all the options without having any effect on the 56M option.
Just my 0.02
Chris