The CM15a has a real problem: it loses its downloaded timers and macros every other day when disconnected from its USB connection to the PC. Maybe they recalled it and fixed it in the last year or so (mine has sat on a closet shelf during that time and I haven't paid AHP any attention.)
If you can leave a PC running to keep the stupid hardware from "going South", it is a wonderful controller. I recently dusted off my old CM15a as I was tired of the slow CM11a. I was using the CM11a with this ridiculous open source app called Misterhouse. If you have never downloaded that, it is a good idea that started in 1999 and went nowhere until about a year and a half ago. Oddly enough, the CM11a portion of the app was unfinished when I downloaded it in 2005. I finished that for them and rewrote a large amount of the rest of the app. I wanted to play sounds and make the PC speak over the PA (as I see a lot of people struggling to do here) and finally patched up MH enough to do it (for five years or so, this app was hosing up people's mixer settings in Windows, leaving one channel on and one off, ugh.)
Anyway, now that Misterhouse is almost competent (the feebs in charge of the source code integrated most of my changes, but typically stopped short), you might want to check it out. I recently submitted a CM15a module that actually works (they have been trying to go in the back door for years, so I downloaded the SDK and went in the front.) In fact, it opens up everything that AHP either doesn't do (react to security devices, speak, play sounds, etc.) Has a Web server too, but the Web interface is from the turn of the century and was a laughingstock even then. I rewrote that too, but these people are sloooooooooooow in implementing anything (somehow they have the attitude that the app must be good if they have been using it for seven years!)
The best bet for a stable system is to leave the controller plugged in to the PC. Use the AHP software for nothing other than downloading timers and macros. Then close AHP, run Misterhouse and literally tell it (it does VR) to synchronize with AHP. All of the information about your ActiveHome is pulled in and turned into Misterhouse "table files" (the Linux geeks that originally wrote this love to edit INI files or they hate to finish programs, can't write dialogs, etc.) and a PERL script. The PERL script has "hooks" for user code.
You have to know a little PERL to do this at the moment (at least to write software extensions to the macros.) That will change soon as I have a floor plan editor in the works.
Don't sit around waiting for the AHP programmers to discover the sound API or SAPI, etc. They are obviously brain-dead when it comes to Windows. Speaking of brain-dead, how stupid is it that this app can't send a preset dim to a Smarthome product? I map the "decorator" style switches to my Smarthome packages so that MH can control them properly. Scenes work too (as we all know, AHP has never heard of scenes, even the X10 extended code versions.) FWIW, the Smarthome scene scheme is simpler to implement and extremely powerful. It is amazing to me that there are millions of people out there struggling to send multiple X10 commands in response to motion sensors and wondering why it doesn't work. Use scenes and you send one command, which every module in your house responds to in a pre-programmed manner, including the ramp rate. Misterhouse has excellent scene support (now.) Somebody copied the raw codes from the Smarthome manuals verbatim a few years back and called it scene support. Recently I submitted new packages to make it easy to program as well as trigger scenes. And the best thing about scenes is that once programmed, they are part of the house (no reliance on the CM15a or a PC!)
So why do I use AHP at all? Just to download the macros and timers. I don't believe the SDK makes that interface available (though I could be wrong as the CHM help file I got with the SDK doesn't work.) The rest of the program is a freak show (how about that door at the top that opens and closes and opens, ad nauseum!?)
Speaking of freaks, MH is still a bit kooky in its free version. These guys who "manage" the source code with handles like "neato-super-mh-genius" are too slow to keep up with the updates. I haven't yet decided if I will release my project as an MH overlay (MH Pro or something) or purge the last few bits of original MH and call it my own (the tail is definitely wagging the dog at this point!) And oh BTW, X10 is just one small part of this app. IR, Email, Instant Messaging, VR, speech, sounds, XML-based news clipping, TV guide, etc. are a few of the bases covered. As I mentioned, some of them are covered with drool from the washouts that are standing on them at the moment, but that should change in the next few months... A schism between the largely Linux-based losers who are clinging to their "masterpiece" and the Windows users who hate like hell to use that version (as opposed to mine) is quietly developing.