Microsoft have the resources that more than likely you don't have. They can therefore implement solutions that are out of reach of most of us. That said, you can do some of what they do. This is particularly true with other output formats rather than CHMs.
I'm definitely open to other formats.
We've been meaning to do a webhelp, but it's been backburnered due to other tasks, plus I've had trouble understanding how webhelp projects work, as our .chm help system has roughly 20 or so separate .chm files linked into one parent .chm file.
I'm used to deploying that single .chm file for each project, whereas each webhelp build seems to produce a ton of files and I'm not sure how to get all 20 projects converted without having an unmanageable # of files and folders to work with.
AIR Help has a Vista lookalike skin that might be what you want. However you face some issues.
At the moment you are using merged CHMs and I am assuming these are installed locally on the users PC. AIR Help can be local or web based but the two forms have different features. Merging browser AIR Help is similar to merging WebHelp but I'm not sure about merging local AIR Help.
You also need to recognise that any other format than the current one will required the calls to the help to be changed. If looking at WebHelp has been shelved, likely any other format will hit the same argument.
See www.grainge.org for RoboHelp and Authoring tips