I think, when one is seriously into photography, he/she at one point of time comes to know that with a particular camera, the saturation point has come and one has extracted all kind of photography that that camera could provide. Its only then the time is to switch to next level in photography. I have used all kind of cameras so far, auto focus, compact, 35mm slr, digital compact and am now using alpha 200 by sony. My experience has been that once I felt that I have seen what all my present camera could do and a better camera is available in the market and is within my affordability, I opted for the next level. I am with my Sony Alpha 200 for the past six months now and know DSLRs offer great flexibilities. (my earlier experience is with Minolta Dynax 4). So, one has to feel the need to switch to next level by sensing level of saturation with compact camers.