[agarsev]

Interestingly, one advantage SignWriting may have over IPA is that while you cannot easily represent sounds in a visual medium (thus letters are mostly arbitrary) movement and hand depictions in SW are highly iconic.

Also, just as you can drop many IPA symbols and just get the basic set needed to represent a particular language, I guess you could use "simplified" SW ignoring the fine differences.

[WorldMaker]

Though a sign-writing still has to contend with lack of a third dimension, it's still a projection like IPA from one medium to another. Certainly an easier to visualize projection, but still a bit like a map projection not entirely capturing the globe.