I have the older RCA Lyra with 128MB that uses SD/MMC cards. The newer one has 256MB of RAM and I think is still around a hundred or so. With or w/o the SD/MMC card it can be used as a USB drive, and with the latest firmware it will play the MP3 Pro standard that compresses batter than the standard MP3. Smaller files that sound the same, or better sounding for the same encryption rate.
The 256MB version is identical except for the color, and the additional 128MB of RAM. I and another guy have these and have had no real problems with them. I did have a firmeware issue with mine for a bit, but it was resolved easily. The first firmware revision that allowed the MP3 Pro would sometimes cause the player to shut off randomly when playing MP3 Pro songs. It was fixed in later versions, and I've had absolutely no problems with it since.