I've been using WHCC for prints, and their ICC profile is Adobe RGB (1998). A local photo lab says they require sRGB and that "sRGB is the standard for photo labs everywhere you go." It is? That's news to me.
My problem is I give my headshot clients their final images on CD in RGB, not sRGB. If they get prints done locally they'll have to pay $10 extra to have this main lab convert the files to sRGB.... OR I could do it, but that's an extra step for me, and I do offer the printing services (via WHCC) at competitive rates as a courtesy. I can't anticipate every ICC profile for all the various places they might choose to use, yet I want to provide files they can use most everywhere.
sRGB is the standard for "bargain" labs. More robust labs will generally have printers that can take advantage of the extended gamut of a larger colorspace. That said, we generally deliver JPGs in sRGB because our clients will not be using the better labs.
smugmug does the conversion for you; converting RBG and aRGb to sRGB for their printer. It did not catch the wide gamut I was using though and caused a minor issue, since resolved.
sRGB is the safest RGB color space to give to uninitiated, color unsavvy clients. Certain images *may* see a slight benefit in some colors using Adobe RGB, but most will see little if any difference, even on high end printers. As long as the lab, any lab has their color management act together, it really shouldn't matter whether they get sRGB or ProPhoto RGB. Their software should do an automatic conversion to their printer profile as the file is sent to the printer. It might be time to buy a good printer for yourself. I have not used a commercial lab since I got my 9800 a couple of years ago.
