The thing you need to remember about wireless in-ear systems is the frequency response. Even the "step up" Audio Technica M3's that I use have a limited bandwidth, so investing a bunch of money on super high fidelity ear buds is somewhat (not totally) useless. About the only game in town that's truly offering a real, full bandwidth system these days is Lectrasonics, but you'll be poying out the nose for them. Even the super high end Shure systems top out at about 16k. The biggest difference you will notice in higher end ear buds is going to be in the mid range, which IMO is the best reason to give for getting multi-driver systems. The more separation you get between the different passbands, the more intelligible the mid range will be.
All that said, the Westones are good. Also look into the Future Sonics, and Ultimate Ears. Most sound guys that I get to talk with this about prefer actual driver based systems vs. armature based systems.