RE: dx7 or x9303
The DMS2 radio stuff is the same in both tx's. Resolution is not necessarily related to speed but defines the number of "steps" if you will that the system is capable of using, basically a finer control.
The X9303 (not the XP9303 with a 2.4GHz module installed) will run in a 2048 resolution when used with a 9 channel rx like the AR9000/9100 or the JR R921. When the X9303 is used with a 6 or 7 channel rx like the AR6XXX series or the AR7000's, then it works in 1024 resolution.