Funny you mention this as i was just thinking about this yesterday.
Sadly, i think the q-jet's popularity is waning----which is ironic/strange as it was equipped on so many production cars---even some fords and mopars as you know.
The holley's (and clones) on the other hand, seem to be just as popular as ever and will probably always be.
i like the q-jet and other rochesters, although even i admit that i was eventually planning on going holley. One reason i haven't already is because my manifold only takes spreadbore and manifold selection for my engine is pretty slim----chevy 4.3 v-6. The 4175 might be too long to fit (may hit the dist).