which class micro sd card for bionic?

[wulpulr]

my bionic came with a 16 gig class 4 micro sdhc card. everything i have read, on camera and camcorder sites, says you need a class 6 for good hd video. should motorola used class 6 cards in the phones? when i get a 32 gig card would i benefit from a class 6 or 10, or will the bionic not send the data to the card that fast and just stay with a class 4?

thanks for any info.