That's exactly why Outlaw made a change to the behavior of the surround mode buttons in the new firmware. You can press the Stereo, Dolby, or DTS buttons once and the front panel will display the current surround mode. Pressing subsequent times will cycle through the available modes. You can also press the "Surr Mode" button on the front panel and the current surround mode will be displayed, if that happens to be convenient.
Since you have an MX-800, I'll share a trick that I've used with both my old MX-500 and my current MX-700. Each device includes some buttons for my TV and my processor: a TV input button (since I use both a component video and a DVI video output from the 990, although my macros normally take care of switching the TV), TV aspect ratio commands, and the 990's surround mode buttons. That way I can control the surround mode without leaving the device I'm on.