I have an RX 20 yet... And still great machine, but the weight was a factor as to why I was less likely to take it off the van when I really should have used it. And it did leave the carpet wetter than my now Rotovac 360 XL's. The XL's are about 25 pounds lighter than the RX 20.
The RX you will probably find more all around useful on a number of commercial jobs because of the skids but I find a lot of commercial jobs a Zipper now or good glided wand doing as well... Or actually better.
I like the Rotovac 360 XL a lot though because it is also very versatile for different heads and again the weight. It also collapses down and fits in my vans better.
The inventor of the RX 20 and Rotovac 360 XL calls the RX the great, great grandfather to the Rotovac 360 XL.
My RX 20 has paid for itself and it sits in the shop a lot, but I will keep it for some rare occasion... But my Rotovac 360 XL's clean so well and leave the carpets so dry, it is a very rare occasion it comes out anymore and play