Yes, the better quality/speed of the card you use, the better your experience will be. We consider Video integrity to be vitally important, so we have spent some time devising a sophisticated algorithm which will automatically turn down the quality of video if the card is too slow, so you should never lose video by using a poor card, but you could lose video quality.

Also, worth considering is the time taken to transfer the video files to your PC. In a testing/qualifying/race situation, you may not have much time between sessions to spare, a Sandisk 'standard' grade card will transfer about 5MBytes per second to your PC, so a 2G video (1 hour) will take around 7 minutes. If you use a Class 6 SD card (eg. Lexar Professional 133x), then the transfer rate is around 20MBytes per second, which will take around 1m 40s, which is much more manageable during a race weekend!

Most modern USB readers will be plenty fast enough, we have used Kingston multi-format readers (19 in1) and found them to work well with class 6 cards.