Both AA and ICP are fine units for fire assay finish. Neither are overly difficult to learn, but not buy reading a book. Hands on instruction is very beneficial, as there are may small techniques that must be observed. I have owned and operated both extensively, and prefer the AA for strictly cost reasons. They are much cheaper to buy and repair. The foot print of the ICP is huge also. If I had to pick one for strait fire assay work, I pick the AA.
only my opinion of course.