As you will have noted, the page that you link to mentions some applications that, unlike Keyboard Maestro*, have been written to take advantage of Apple APIs that are not “public”. You can of course use these applications in conjunction with KM: for example, set up a right-command trigger in BetterTouchTool to send an Applescript message to a KM macro.
There have been a number of related discussions about app launchers and how they might be emulated in KM. Have a trawl through subject headings from the past 6 months or so. In particular, this discussion about Leaderkey may spark some ideas.
* See Peter’s reply in a related thread for an explanation of this design decision.