The keyboards on Inca Roads (in the beggining) are totally zeuhlish... The chirpy, highly modulated kind of thing, similar to something you'd hear on Udu Wudu or Attahk. Of course, that song has an extra-terrestrial subject matter...
Of course, I wouldn't accuse FZ of ripping them off or even being under the influence of Magma... But I would be surprised if he had never heard their music. If anything, like the previous post indicated, FZ was an influence on so many people. I addition, Daniel Denis of UZ claims Zappa influence... Of course, these are mainly European bands...
I read an interview with Dwezil about the Zappa plays Zappa tour. As you may (or may not) know, the tour started in Europe, and there was some ambivalence about brining it to the U.S., because most Americans are familiar with "Don't Eat the Yellow Snow" and most of Zappa's toilet humor, and not so much the great stuff he did...
Nonetheless, I am glad they are playing in the U.S., and I look forward to seeing them this Saturday! They've just gotta play Peace Corps... It's so fitting...