Raw + Jpeg was originally intended for pro's with clients on hand or art directors/creative directors who have laptops on hand and want to see files OOC. Most art directors who dont have raw software may or may not be able to open a raw file on their laptop computer, plus download time... time is money, right? So the idea is you throw in the card, download the jpeg, opens in seconds, and opens in just about any image program... art director see's what you have, gives critique and pointers on where he wants the shoot to go from there... if the scene is tickling his fancy or if he wants to go in another direction. It's a down and dirty quick soft proof for clients or that was the thinking of it... The 2 cards helped streamline it so you can take out the backup card and not disturb the original in case you need to continue shooting, and why the SD card? It's cheaper? I personally dont see the appeal but to each their own. I'm a professional and shoot large jpegs from time to time depending on what i'm doing, what my original output is meant to be, and whats going on... If it's for print, or if I get that hunch that I want the original for my portfolio, I shoot Raws... if I have a client who wants photos for their website, screw it, i shoot jpegs... If it's for small prints, jpegs... If it's down and dirty chasing my kids around for the heck of it, jpegs (I can fit more jpegs on my cards than raws)... Plus I have tested tried and true settings on my jpegs where I dont lose much info, plus the extra time going through ACR/DPP to process the raws, unless it's worth my time and time (money), then I shoot raw.. when it's not, then i'm fine shooting jpeg if needed.