HomeSeer resells a lot of leading hardware and only manufactures a few Z-Wave devices because of a need/demand in that field.
HomeSeer has always been an open and extensible system. Pretty much anything can be integrated in with HomeSeer using its scripting system (which supports VB
scripts, Perl, Python, etc.) or tighter integration through a plug-in interface which can also be written using your favorite language. With over 200 plug-ins (many free), there may already be an interface to several things in your list or to a technology or device that you can use. I do not believe anybody has posted a Rhapsody plug-in for sale, but there may be a free one. Plugins exist for iTunes, Windows Media Player, WinAMP, etc. which may have their own Rhapsody integration, or some of the more hardware centric music interfaces such as NuVo, Russound, Media Center, Roku, Sonos, SqueezeBox, etc. may have it.
Once your hardware platforms are integrated into HomeSeer, there is a variety of ways to interface to it including that very extensible script, ASP, ASPX, and plug-in support that would allow you to roll-your-own if you so desired. HSTouch is a great touchscreen client with a powerful designer to create screens from scratch or from templates, and clients exist for iPhone/iPod Touch, iPad, Windows CE, Linux, Windows, and Android.
If you care to talk specifics with other users, visit the HomeSeer message board where over 30K users are available to answer any questions you may have - with many of the free plug-ins and scripts being posted to the message board, it is one of those undocumented "features" of using the software.
I'm sure it's not an easy decision to change course, but good luck with whatever you decide. Remember, it's not about what works best, it's all about what gets you the highest WAF.