The Rx is a good machine. I think it does better on residential carpet than cgd. It takes too long to rinse and way too much moisture is put into the air in the form of steam. It does take longer mostly due to detail work and longer time to flush.
I'd rather run a greenhorn myself, you have faster flushing. Less steam....better drying but not by much I'd say but I haven't done any tests to compare that one. The RX uses way more water. It's really hard to say what does a better job cleaning, I'd give the edge to the Greenhorn.
If you have a solid day of non stop work I can see how a RX can save a ton of fatigue. I'd say it comes down to prefrence and situation. You can easily just prespray, and rinse with an emulsifier and do a pretty good job. No prescrub or much dwell time needed. Oh and the RX lift the pile up way better than a glided wand....I haven't tried a slot
glide on a greenhorn to compare that though.