The built in scanner tools did a better version of reducing the moire, but the IJ Scan utility seems to have done a better job at retaining the original colors at the cost of the whites washing out some of the detail in the brighter areas. It's a bit of a judgement call, but I personally think the built in tool did a better job overall, since the minor color difference can be corrected digitally in Photoshop.
One other word of advice, if you aren't doing it already, use a book or two to weigh down the cover when you scan it. It will help flatten the image (and the spine in particular) and eliminate the "flash" you can see reflecting in the IJ scan.
And most of all, thank you so much for making scans!