"But one thing I really noticed that when usingCMYK & SpotorAs Iscompared to the Press Quality PDF default color value ofCMYK[only] is that my output matches better to what you'd expect it to be. No color shifts between the color in the EPS file I bring in to Quark and a color block I create using the spot color. "
If I read this correctly, you are seeing inconsistent CMYK values in your PDF between Pantone colours in your EPS and the same Pantone colour used in a quark generated block.?
Its been like this with quark since v7, the fix is not to use names that matchQuark's color libraries, so instaed of PANTONE 282 C change it something like SPOT PMS282 C.
If you ask for just CMYK then the problem is compounded as Quark tries to convert the Lab or RGB to CMYK, it is probably starting from two different sets of numbers (one buried in the EPS, and one extracted from its color library), or possibly using two sets of profiles (one taken from the settings for the picture and one from the generic document)or possibly just failing to get hold of the EPS data entirely.
If you use [b]AsIs in theory you pass the data through without conversion and should end up with the closest result, not sure about mixing Lab and EPS, but if its possible you'd end up with [b]DeviceN Lab values in the PDF, and even if the two are different (one from Adobe one from Quark) they'll be close.
Last time I ran some tests like this Spot colour gradient in Illustrator PDF placed into InDesign (CS3 or 4 I think) I ended up with [b]nChannel Lab values in the Exported PDF, so getting the best possible result, and of coures ID and AI share the same color libraries so no chance of getting the conflict you get with Quark.
I would recommend sticking with [b]AsIs every time, and if possible only use spot colours without PANTONE names, if its not possible ask your printers to remap the PANTONEs in your PDF to a common [b]Alternate Color Spacebefore attempting proofing or converting to cmyk, but do it all in the PDF using Pitstop or PDF Worklow[:)]