I'm looking for some advice as to whether it is worthwhile to switch from my XSI to a 30D or 40D. I'd love to move to the 50D, but the cost (even used) is prohibitive. My primary motivation for switching would be to get a better frame rate and a greater buffer for continous RAW shots. My XSI does a decent job of capturing my kid's soccer action , but I'd like the camera to help compensate better for my own poor sense of timing. Does anyone have any experience as to the quality of shots between these three cameras? I'd hate to take a significant step back in IQ to get the faster speed. Should I hesitate at all in making the switch? Am I too caught up in megapixels? Am I showing my inexperience? Thanks in advance.