I'm also getting 2.3cpm for RDM, but it seems that as a UA Gold, I need to buy a LOT of miles at a time. It'll show something like 15,000 miles for $345 for an award ticket, but once I enter my MP#, the total jumps to 50,000 - as in, I need to buy a minimum of 50,000 miles for $1,150. Thanks, I just needed a few thousand.
On the other hand, when I check the award accelerator for smaller itineraries (i.e. not many miles), I get instead 3.1cpm, and still need to buy a lot of miles to get even that rate.
Before I was Gold, I could buy far fewer miles at better prices. UA, it seems, wants to make sure elites have lots of opportunities to spend a lot of money.