When you want to switch to DSLR. That is because: 1) You want higher quality images. 2) You want to be able to change lens, add flash light and have micro function (even super magnifying function with extension tubes). This means you are buying a system, not only a body/a lens. You probably wish (in the near future) you can afford another tele lens for shooting birds or kids... You might want to add a bigger flash light for shooting friend's wedding... or a micro lens... The more you buy,eventually, the more you become get into one brand, means more difficult to jump to other brands... YES, You are stuck... unless you want to start all over again. Example. A very famous wildlife photographer Art Wolfe, He mentioned the courage he got from switching Nikon to Canon was from a thief. He lost everything, includes 2 week's field work result.
Anyway, just want to address that choose a suitable brand is very important for DSLR. A lot of people recommend buying big names. The reason behind it, is you can get cheaper price for their quick updated strategies. You got more used equipment opportunities in the market. They also have full line of different little things, even other side brands make "things" for those big names.
Don't think you just want (and will) use one body/lens... You will surprised how quick you change your mind after you start browsing photo website. Although high quality lens are always expensive. You also can get some super value/ quality lens from the DSLR. e.x. 50mm/f1.8 cost $60, awesome lens.
When refer to pixel, I do think over 8 mega pixel is nessary though, IF you want to sell your photo to publisher. I know some of the publishers set the line around 8 mega pixel. If I remember it right, people in the print industry told me the film quality (ISO 50, Fujifilm Velvia ) would be equal 12-16 mega pixel.
However, I do agree 6 mega pixel is already plenty for webpage or some post manufacturing.
(keep talking...) The other factor have been overlooked in DSLR is the image quality that other than pixel value. I don't know have you guys noticed that even your pocket P&S are equal pixel value to another DSLR. The image quality looks different (the color gradient, dark corners...)... It might due to the fact that the pocket P&S has smaller lens/and smaller sensor. Thus the image doesn't comes out as good as their DSLR companion.
Be honest with you, P&S or DSLR, all good. Just depends how you use it... I do have a 1.3 mega pixel P&S. It about the size of a sushi. I always have it in my front pocket... easy reach and easy use. I have the DSLR in my backpack. When some shot of lifetime appear, I won't regret...
I am a biologist grew up with a fishing rod in my hands. I have been fortunate enough to embrace my love of art and science in my career. Most of my free time were well spent in the nature, either studying bird behavior or chasing variety of fish with fly rods. My favorite art medium is watercolors, I love the natural and spontaneous feel created by watercolor pigments. I am currently a post-doctoral research fellow at Harvard University. Welcome to my website. Mark