I successfully updated my DS2072A to 200 MHz and all options following Giggy's summary.
Like a few others, I can't get 300 MHz to work - NSEQ (200 MHz) works OK, but NS8H doesn't (anybody know how to fix that?)
For others who are going to do this, here are some tips to go along with Giggy's PDF:
1 - When powering-on the scope for the initial firmware installation, you need to press HELP twice in VERY QUICK succession immediately after pressing the power button. If it doesn't work, it's because you didn't press HELP twice quickly enough.
2 - It takes a while for the firmware to update; be prepared to wait for a while (4 or 5 minutes) - the CH 1 light will flash until it's done.
3 - The way to check if the new firmware was installed is UTILITY > SYSTEM > SYSTEM INFO, but that does not give the full detailed info you need.
To get the detailed system info (from the hacked firmware you just installed), Giggy says to press [Menu 7] [Menu 6] [Menu 7] [UTILITY]. (And then SYSTEM > SYSTEM INFO).
On each side of the screen (left and right) there are a row of buttons under the MENU button. The first one under the MENU button is "1", the next down is "2", etc., to "7" which is the bottom button.
So [Menu 7] [Menu 6] [Menu 7] [UTILITY] means press the bottom right menu button (Menu 7), then the one above it (Menu 6), then the bottom one again (Menu 7), then UTILITY. Press them one at a time, but VERY QUICKLY. If you do it slowly it won't work. Then press SYSTEM > SYSTEM INFO.
5 - The link Giggy gives (to rigol.com) for the Ultra Sigma software goes to version 00.01.05.09. On the CD that came with the scope the newer version 00.01.05.10 is there (I used that). Supposedly the newer version is also on the batronix.com website (I didn't try this). [Also the Rigol website downloads very, very slowly.]
6 - The Rigol documentation README for Ultra Sigma tells you to first install "NIVISAruntime.msi" before trying to install Ultra Sigma.
I'm not sure this is really needed - I think the runtime is now included in the Ultra Sigma installer.
But I installed using "visa520runtime.exe" (from the National Instruments website); that worked fine.
7 - I found Giggy's explanation of using HxD a little confusing. Giggy talks about three "columns"; left, middle, and right.
The "left column" is the hex offset into the file (the address); this is on the left side of the screen in blue. The "middle" column is the central area with 16 8-bit hex values in each row. The "right" column is the right portion of the screen showing the same data in ASCII.
So, paste in the "massive string" that appeared after the serial number (don't paste in the whole message - just the long hex string from after the serial number) into the hex section (middle), then the serial number in ASCII goes after that (on the right), and finally one byte of zeros in the hex area.
8 - When entering the code into Ultra Sigma (Giggy's last step), enter it without quote marks. For example:
:SYSTem:OPTion:INSTall R939MBGNR63H279H993PXZT49K4M
(don't use that exact code; it's just an example - use the code you got from rigup)
I hope this is helpful to somebody.