I’ve also found if you buy higher quality “fast” memory cards it reduces the time needed to save the image and picture to picture the wait is less. I believe i bought the kingston Ultra series. I saw a noticable save time difference.
Another advantage of dSLR cameras is that they are instantly ‘on’ when you flip the switch; no lag time while the processor talks to itself. I can snatch my Nikon off the seat and shoot without missing the action or the light, whereas with the Olympus it’s a nearly five-second wait between pushing the power button and having the camera come on line. There’s also the matter of what I call ‘screen freeze’ with lower end digitals. As you push the shutter release, the picture freezes even while the action shifts. You’re not really sure what the hell you’ve captured until you do a review of the shot.
Most consumer digital cameras cannot take any advantage of faster memory cards. There are probably some older/cheaper cards that are slow enough that they become the limiting factor, but in many situations the limiting factor will be the camera’s write speed. This is particularly true for the cameras with smaller image sizes. Once you get to larger image sizes, faster memory cards are clearly a good investment.
For example, my SD300 (4 MP image) can operate at full speed with a standard Sandisk card, I didn’t need to go to the Ultra-II. But the SD500 (with a 7 MP image) will take advantage of the faster cards and allow it to keep going at burst mode indefinately.
Having said that, for most cameras purchased today, the basic memory cards are still fine. You are correct that certain manufacturers basic cards are faster than other basic cards, going up to the next “level” isn’t always needed to get better performance.