Overall it's clear that there are real differences between different brands. The unfortunate thing for the consumer is that the cards which are promoted as high performance tend not to perform any differently than many 'standard' cards.
This really does bring into question the whole concept of charging a premium for such cards.
The other noticeable difference is in the device's ability to make use of the cards performance, your camera and its CF interface has a large influence on how a card performs.
Many cards will perform better in D-SLR's and especially professional digital SLR's (most professional D-SLR's can push the results shown by the D30 by 50-70%).
Detto questo, il punto è spendere meno... una volta che si comprano marchi abbastanza noti (kingstone, viking, ridata, sandisk, trascend, lexar... ma anche marchi meno noti), ultra o non ultra, la differenza non si vede... se, come su fotodigit, allo stesso prezzo puoi prendere la ultra e la normale è ovviamente meglio prendere la ultra... altrimenti, se c'è da pagare la differenza "This really does bring into question the whole concept of charging a premium for such cards." e non aggiungo altro