Yesterday there was a question about the preview of Pantone colors in Acrobat (Indesign Pantone 262 U problem) which got me to take a closer look at a color problem I've noticed in the past but didn't pay much attention to because I never use the Pantone system for process color jobs.
If you use Ink Manager to convert Pantone solid spot colors to CMYK in CS6 or later you get a color managed conversion from Pantone's Lab color to your document's CMYK space. Works great when the color is 100% and produces the same result you would get if you manually converted the swatch to a CMYK process color.
However, you don't get the same result if tints are used. The difference can be so great I would question ever using Ink Manager to convert Pantone solids to process. How bad the separation values are seems random but is particularly noticeable with dark saturated colors—you would surely see the problem with 262C but maybe not with 659C where the hue doesn't shift.
Here's a screen shot of some various Pantone color tints exported as a PDF/X-4 to default US SWOP Coated CMYK. On the right I used Ink Manager's All Spots to Process, on the left I changed the swatches' Color Type from Spot to Process and let InDesign make the conversion from Lab to CMYK on export. The circled 262C 30% tint converts to 21|19|16|0 via Ink Manager, which be almost a perfect neutral gray on most presses and wouldn't have the violet cast you would expect of a 262C tint. The version on the left where the swatch was set to process is a clearly better and expected conversion at 20|26|13|0 with more magenta and less yellow.
You can see similar problems in all of the other tints. Here's a zip file of my examples.
http://www.zenodesign.com/forum/InkManTest.zip:
