My HTC Rezound has learned a new, and not good, trick. It keeps switching down to 1X data rate. Once it gets there, the only way to get it back to 3G is to restart it. Sometimes i have to pull the battery.
I went into Verizon today and the kid told me that this is a problem with all the 4G phones. He said there is a firmware upgrade coming. He offered to replace the hardware but I didn't take him up on it, because I doubt it would make a difference.