Could anyone tell me what the differences are between the E series and A series P2 cards? I assume the A series is somewhat different then the older R series.
E-Series is supposed to be cheaper (though A-series can be had for a few hundred more now), and uses a faster type of memory, so offloading and editing from the card is faster at the cost of a shorter life cycle (5 years of a single daily fill-up). The e-series cards will work in any p2 device (though firmware upgrades might be nessicary in some cases).
