They recommended the RS120, but that looks like a dated product so I'm digging further into the RS135 and RS 165.

Good references.  I also found:   http://www.presonus.com/community/Learn/The-Truth-About-Digital-Audio-Latency   http://www.practical-music-production.com/audio-latency.html   I've sent a request to Sennheiser to see which models have less than 10ms latency.

Do you know if there are any issues with latency?  This is obviously not an issue listening to recorded music, but with live music, latency is very very annoying.

I play an electric piano at home and I'm tired of having a cord interfere with the keyboard.  My keyboard has a standard 1/4" headphone jack and I'm looking for wireless headphones which will let me hear the full quality of my instrument.  Not terribly price sensitive, but my experience is that...