As @Walter mentioned before, your USB2 will simply not allow you USB3 speeds. But that alone is not a huge issue, you'll simply wait more when you dump stuff off your CF card.
Now, regarding which CF card to buy, it's easy... If you have the money, go for a Lexar/SanDisk (assuming you're chasing ML RAW). If you feel that's too much, you can play with KomputerBay/Transcend. There's a new Toshiba Exceria in the mix, but it's expensive...
Hope that was some help...
Valid in every sense. It's a solid suggestion. There are failures in every brand, we just tend to see more complaints with KBs--doesn't mean they all fail. At least you got suggestions on ML of what to avoid, if you have a little time to research.
The writing speed in order to achieve success is important. While that does not mean you must have the newest 100000x card, it does mean that the controller must be able to sustain a high write speed. If that didn't quite make sense, then this might clarify: the reason CF Cards have been around so long is because they have built in memory controllers. When CF reached speed limitations, they upgraded to faster controllers. You get some super fast cards, but those bleeding edge controllers are EXPENSIVE.
I spent some time searching for card benchmarks and learning about the capabilities of cameras before I settled on the 50D and a Lexar 1000x 32GB. I had to know if the 2008 50D could really keep up with the Lexar 1000x speeds. I ended up taking an educated gamble and being successful. I still knew, coming in to the fray, that the 50D supported UDMA7, and that it was initially reporting 60/s on the ML RAW chart. I knew that it did not support ExFat. I learned all this here. The gamble was that I guessed it was the same as the 5D mkII CF Card interface, and my gamble paid off, as I get 82.9/s continuous with the right ML release. I owe that to patience and research, and not frustrated whining in forums because nobody had all the answers. Forums are about sharing information, not just pleading for it.
If you have more money than sense, don't settle for less than the Lexar 1000x 32GB. Expect to pay $120 for it. Maybe more. That being said, there are plenty of KomputerBay success stories, even if some come with a little effort. It seems vintage has been a concern. If that's something you don't have the wisdom to deal with, nor the patience to learn, Lexar, Hoodman, and SanDisk need to be names you spend a lot more money on in order to gain a bit more peace of mind.
