Just to clear things up... you're asking about any speed differences he might have noticed between the Macbook Air and the Mac Pro? Right? Ok. Yeah.
Err ... I was only asking about the hard disk drive comparison not the whole system. I think you need to re-read what I wrote.
I'm sure I remember reading a review on the net that said that the SSD was actually faster than the hard disk drive in a Mac Pro for certain situations and I was interested to know how it fares in real world usage NOT which system is faster for advanced simulation work or 3D rendering ... there's no comparison.