Just got my Pace-Car I modified to work with the Touch (Steve also modded the Touch). My main reason was so I could play hi-res files in native resolution.
I can now play all typical file types, 16-24 bit, up to 96k, in native resolution.
First impressions:
The Touch: Like the Touch in general. It is a little more heavy and solid feeling than I expected. The touch screen works well, although I have a few quibbles with it. The included remote doesn't have a screen, but works well and is useful. A better solution would be a Duet Controller or an iPod Touch/iPhone as a controller (there's an app for it to work as controller for Squeezebox).
One useful feature of the SB Touch: it has a reset/restart button on back. Very useful when paired with a Pace-Car, as the Pace Car has to be turned on first. The reset button allows restart of the Touch, so you don't have to unplug it everytime you turn the Pace-Car on and off.
As far as the sound: quite good. I don't really know how it compares to my previous Duet overall (as the Duet is not compatible with the Pace-Car), but 24-96 material definitely sounds superior to what I heard through the Duet (with downsampling done by SBS), and also sounds much better than even native 24/96 playback from SPDIF out of my soundcard>Foobar (kernel streaming)>to DAC.
Conclusion: the SB Touch+Pace Car is a good combination. With a Pace-Car II I'm sure it would be even better.
Sound is much more dynamic and fuller sounding, improved sound stage. Straight SPDIF from my PC Soundcard (M-Audio 192) sounded a bit lacking and thin in comparison.