Price source: www.etrailer.com
The Pro Series 20K is the el cheapo for $600. Skip that one. (I threw away a 15k Pro Series and replaced it with a 16k Select Series.)
The 30867 is the new R20 for $775. It meets all the new requirements set by somebody. It's wonderful.
The 30081 for $720 is the old classic or Select Series almost identical to the 16K I used constantly for towing over 100,000 miles over 10 years. Works great. I don't know the changes made in the R20, but I doubt they are necessary to have a functional 5er hitch.
I guess it depends on how much that $775 vs. $720 means to your budget. I'd have no problem paying $720 for the 30081 and know it would last for years and years. But if you have an extra $55 floating around you can spend, then get the latest and greatest R20 for $775.
But skip that Pro Series. We can't have a retired Super Sergeant driving around with an el cheapo 5er hitch.