There are a lot of theories that people argue about in photography forums like DPReview, Luminous Landscape, Photo.net, etc. Some examples you'll read about a lot:
These are just some of the issues that people have very strong feelings about and are willing to argue. Sometimes, the arguments get personal and really nasty.
I always shoot RAW. I understand why some don't. I know from editing thousands of photos that Dan Margulis is wrong as a factual matter when he says photographers can edit in 8-bits and not expect serious problems. I have seen too many photographs that degrade visually when the JPEG version is edited and do not when the 16-bit .PSD or .TIFF is edited.
Dan is right for many photographs. You can edit an 8-bit JPEG, print it, do the same with a 16-bit .PSD or .TIFF, and get equally pleasing results.
Dan Margulis is at the center of another argument. The desirability of working in L*a*b. He argues, you can go to L*a*b, make significanrt edits, and return to RGB without visible artifacts. On the skeptical side, there's Andrew Rodney. He warns against unnecessary L*a*b conversions and what can happen with a round-trip through the Adobe Color Engine.
In my recent video, Color: It's All Relative, Part 7, L*a*b and Back Again, I demonstrate that Andrew Rodney has the better argument with an 8-bit photo and Dan does wth a 16-bit photo.
The really important point, which I'm trying to expand on here in my blog entry, is that a lot of differences in theory turn out to be small differences in the typical case.
Take an 8-bit version of my pseudo Macbeth Color Checker Card, send it to L*a*b. and send it right back to RGB without any editing, and there will be demonstrable damage if you look at the histogram and the numeric information that goes along with it. Would someone notice it, if you print the original and the version with the round-trip to L*a*b. Probably not. Almost certainly not.
Andrew Rodney is 100% right: in theory. Will there be visible damage that anyone would notice or care about? Not very likely from a simple round-trip to L*a*b for sharpening or a boost in saturation. In practice, Dan has the better argument for many photos.
A savvy photographer will have to weigh the benefits that can be achieved from a round-trip to L*a*b against artifacts that might develop, especially if more editing is going to occur back in RGB.
That's the way with many of the arguments in digital photography. People get stuck into taking a position on theory that makes little or no difference for most photographers and most photographs.