I tune with a DS3 and from feedback during the various F.I.T.T. events, the best drivers can detect differences in the way cars were tuned. Many DS3 tunes are considered rather loose by top wheel drivers while tunes done on wheels can seem rather tight to DS3 users. Good drivers will compensate easily for the differences but there is a slight variance in perceived handling based on what a tune is created by.I dunno but I dont think it makes that much of a diference. A well tuned car should handle well on any type of controller. I use a wheel but have no problem when useing a ds3 pad.
I think its easier to find faults in the handling with a wheel though so I would say wheel tunes are better than ds3 tunes.
Try some of my setups if you like, link is in sig.