If you're rolling your own, with limited volume, the development cost for SD will swallow up the cost of those pesky CF connectors, since the CF code is pretty straightforward and the performance is high.

If you want fast SD, the hardware development isn't "free" either, as you'll need a separate CRC channel for each of the 4 data bits used in high-speed mode, and you'll need to merge the streams post-check. That uses lots of MCU bandwidth and causes a large delay, resulting in very low performance. In volume, however, the SD is WAY cheaper and the connectors aren't as fragile, either. If the volume justifies it, however, the SD is every bit as fast as the USB. If you find the interconnection module price too high, it's because the volume is low.

That simplifies your choice, doesn't it?

RE