Since the early 2000s I stay with Toshiba for CF cards. At this time I got my first MP3 player bundled with a cheap card. I was a little bit disappointed because of the short playing time of that device before the batteries got empty.
A few months later I read a review in a computer magazine testing cf cards. I found out that the card bundled with my player was one of the most power demanding cards on the market. According to the test, Toshiba cards were reasonably priced, had a reasonable data transfer rate and belonged to the most energy saving cards on the market!
I replaced the card of the player with Toshiba and the playing time doubled
CF cards have a quite smart memory controller inside. They act like a proper harddisk towards the interface. This memory controller can be optimised for performance or for energy saving. In the case of my old MP3 player for example, the cheap card was not optimised at all and the controller didn't support any power saving strategies. So the power consumption of CF cards can differ a lot. This could be an interesting fact for MPC 500 users which use the device with batteries...
My old digital camera is gone and I don't use the MP3 player anymore. Now, the 2 GB standard Toshiba CF card I bought some years ago moved into the MPC 500. No problems upto now.
Keep in mind that Toshiba, WesternDigital/Sandisk, Micron/Lexar or Samsung are manufacturers of flash memory on their own. Many other companies like walmart buy their cards from these manufacturers or from somewhere else and put their label on it.