The RCA can have 15-step macros on any key except the device selection keys and the setup key. If you get a cable and program from your PC, you get 3 additional devices and the ability to put macros on the device keys. You can also put macros (or any other function) on shifted keys, essentially doubling the commands available on the key pad. On my RCA, I put all my "activities" on shifted device keys, i.e., "Watch TV" is shift-TV, "Watch DVD" is shift-DVD, etc. I put my master power off macro on shift-Power.
In the $50 range though, the harmony is easier to use and program since you have unlimited softkeys via the LCD and setup wizards to help you along. The RCA plus a cable would total $45, and there is a steeper learning curve for programming. It's much more configurable, but you have to do a lot more programming from scratch.
I have both, and each has it's strengths and weaknesses. The biggest advantage of the RCA is if you break it, you're only out $15. Harmony is my main remote, but I use RCA's in other rooms (I have a stack of them I picked up on ebay for $7 each a while back). Even if you get a harmony, an RCA is still nice to have for adding discrete codes which may be missing from the harmony database (I've added dozens of codes that way).