I've RX'd every hwe job for the past 4+ years. Been thinking about getting a Greenhorn because it might be faster, especially with a helper to prescrub. But I don't know whether the tendonitis in both arms can handle a wand all day.
In my experience, a single RX isn't efficient for a two-man team because one has nothing to do much of the time while the other is RXing.
My bud's rig was down for a couple weeks, so we doubled up on mine. I scrubbed, he wanded. Big dude, a (glideless) wanding machine. We did more than twice the number of jobs I do by myself with the RX.
The RX does the best job of anything I've used, but the same results can probably be achieved with a mechanical prescrub and a good wand.