Data communication is definitely lossless. I experimented with one of the radioshack wireless a/v setups last year (I also had a 30 foot coax in my room then). It cost just under $100. I found that it could handle 24/48 just fine, but at 24/96, it choked and didn't output anything. The trick is to use the video (yellow in/output) for the digital audio. Since I needed 24/96 in my system, I returned it.
The data all gets there, but unless your DAC reclocks the signal, don't expect it to sound as good as straight from the soundcard. The output from the little wireless receiver is full of jitter.