Well, I finally took a little time to jot down some thoughts on writing macros.

• Keep the existing status of devices in mind. This means that a power on/off command for a common device such as TV or receiver should not be used as part of the mode changing macros for each source device, as it will only put the device in the correct state (on) half of the time - the other times, it will turn the device off because it was already on from a previous macro. This is also true of input toggle commands such as those often used to control TV inputs. If you know where the device started out ("INPUT 1" as an example), you can send that toggle command multiple times to get to where you want to be ("INPUT 4" after three toggle commands for this example), but if you can't predict where the device will start out then you can't do this.
• Corollary: discrete codes are cool. While you can't use toggles for power and input without some care, you can use discrete codes ("power on" or "input3") quite freely. Source selection macros can send a "power on" command to the source to make sure it's on (and if it already is, it'll just ignore it), a specific input command to the TV (to make sure it's on "video3" for example), and set the receiver or processor to the correct input. A global "off" macro can tell every device you have to power off, and you won't have to worry about stuff that's already off getting turned on needlessly.
• Simple is best. The fewer steps that you include, the less time you'll need to keep the IR emitter aimed in the right direction and the less likely that casual users will be to assume that the remote is finished and set it down or that something is wrong and start messing with it.
• Some devices need time to think about the commands sent to them. When sending more than one command to a specific device in a macro, test it to make sure that all of the commands are received by that device. Consider locating the commands at opposite ends of the macro (turn the TV on, then turn the cable box and receiver on before telling the TV what input to switch to). If that doesn't work, add a delay before the second command and adjust it up and down until it is just enough to give the device time to recover from the previous command before getting the second one.
• Be creative. The MX-700 will allow macros on almost any button, which can create some unique opportunities. Here's an example from my own setup. The Model 990's AM/FM tuner allows direct access to presets by typing the two-digit preset number into the remote. Remembering what preset each station is set to can be a pain, so I created a page under the TUNER device with nine or ten macro buttons. Each button was labeled with the station (92.9, 102.7, 99.7, 98.1, and so on), and each button had a macro that sent the corresponding two-digit preset number to the 990.

For the specific case of the Model 950, the device input commands (DVD, Video1, CD, and so forth) are all discrete "power on" commands as well, so it's really easy to put a command to set the 950 to the right input on the button for that source - even if that's the only command you have there. Likewise, the "Power" button on the 950 is (as you already know) purely a power off discrete code, which can be handy in "power off" macros. My MX-700 file is based on a 990, but the two behave pretty similarly - you can see the macros that I've created on my "power on" and "power off" buttons (top left and right buttons on the remote, able to hold different commands or macros for each device plus the main page). In my case, the main page "ON" button turns on the TV, turns on the cable box, sets the 990 to the cable box input (turning the 990 on in the process), and sets the TV to the component2 input with a little extra delay in there to give the TV time to turn on. The "OFF" button for each device will turn off the TV (using a discrete off code that I found recently), the cable box (since the cable box is assumed to always be on if the system is on), the 990, the Roku SoundBridge (using a discrete off code, even though the SoundBridge is only on sometimes), and if we're on a device not already listed (like the DVD-R, which doesn't have discrete power codes) it'll turn that off too.