Yes, I'm using the newest Dry Creek profiles for both Luster and Glossy. My monitor is calibrated with the Spyder2 suite, and I'm familiar with soft proofing and then converting. The other prints I had done with Luster seemed ok, but two of them were really dark. I took the two image files back and had them printed on glossy. Now they look like they should, but it wasn't a test.
The original files were 66MB tiffs. Last night I wanted to see if the images would be the same quality in jpg, so I saved them as jpeg optimized. Shaved 54Mbps off them and they look no different than tiffs, but I haven't gotten my photographers loop out yet either.
As long as others have experienced darkness using luster and Costco, I know it's them and not me. Also, sometimes they just mess up.
As far as adjustments go, I always write "no adjust, no resize" on the envelops, and then I check the back of the print. There are four numbers that show the adjustment values. If the numbers on the back of the image are replaced by NNNN then there was no adjustment. Mine all said NNNN.
Good thing about Costco is that you can take whatever pictures you don't like back. By the way, you can also take back your wide screen 32 inch LCD panel and replace it with a newer 37inch panel for the same price. I bought mine in March, and now the 37 inches are out for the same price. Before that, I bought a Phillips 32 inch HD TV--huge thing--and took it back over a year later and bought the 32"LCD I have now for the same price.
BTW--the people who work at my Costco could care less about photography, the machine they work with, or anything else. They are borderline rude and are ignorant of all things Noritsu oriented. One employee got so many complaints that they fired her. I was one of them, and several other "professional" type photographers too. I told the manager that I was to a point I didn't even want to come in the store to get pictures done anymore because of that one employee.