quite a while ago I read a statement by Misha Mansoor saying that he liked A5 PUs more for recording purposes while he tends to use ceramic ones for live performances to cut better in the mix. How much truth is behind that?
I think this really comes down to personal preference. As such the statement is true by 100%. As a general rule, I would disagree. Keep always in mind that
(1) pickups are only one part of the entire tone chain, starting with the player, going on with the guitar (and its construction parts), on through the cable to the amp (many, many parts in there, too!) and ending with the loudspeaker and cab, and
(2) magnets are only one part of the pickup besides the wire gauge, wire material, wiring technique and other materials in the process.
I am not saying that magnets do not matter - far from it - but I think the rest of the pickup construction matters as much, and so do the other parts of the tone chain.
Cheers Stephan