These cards are gross overkill, mostly out there for people with too much money.
The main advantage to a fast card is downloading with a UDMA firewire 800 reader. You will not get that advantage with a ordinary card reader, so unless you plan to equip your computer with firewire 800 and buy a reader, don't waste your money, buy a much lower priced and slower reader. 30 mb/s is more than fast enough.