It would be very difficult for most people to pick up subtle differences of a prime vs a zoom, for what has already been said that the quality of zooms is now on a par with primes. The wider a zoom is, the more technically challenging it is for designers to correct for aberrations, very especially at the wide angle end (e.g. the Five Aberrations of Siedel). Some aberrations will be corrected beautifully, but within a cost restraint, others must remain; this is true for even the costliest lenses from Nikon and Canon. The better corrected the aberrations are, the more astronomical the cost. Barrel or pincushion distortion is still very common even on expensive ultra-wide to normal zooms, including my non-rectilinear 17-40 Canon.

The best experience, if it is within reach, is to use both types of lens and enjoy the benefits (and attendant drawbacks) of either. If there was a zoom from, say 45mm to 105mm for my 67, I would probably use it, though I the mind's eye tells me such a zoom would be costly and very heavy — as with anything of the MF Pentax stuff. I'm taking my EOS1N and sole 17-40mm zoom with me on a mini-roadie from tomorrow — no prime on it this time. And of course, occupying most of the back seat will be the heavy-hitter Pentax.