About the existing ASL orthographies such as Stokoe and SignWriting, aside from the issue of copyrighted or patented or whatever systems, and aside from the issue of their not being (currently) known by a majority of ASL signers, I haven't seen the questions addressed (or even asked) (1) are the systems relatively easy to learn if you already know ASL — rather like a phonetic alphabet or syllabary — say with a discrete symbol for each chereme and an intuitive way of handling stress exaggeration or whatever you call the way a sign can be exaggerated in whole or in part (sort of like lengthening a
Yes, in fact Stokoe is easier to learn for ASL users than users of other signed languages (many of the symbols for handshapes are based on which letters use which handshapes in ASL fingerspelling, making it less intuitive for, say, BSL users, although not impossible as it's certainly been used for BSL as well)
SuttonSignWriting is supposed to be easy to learn, but the fact that it has two differing systems (one for printing and one for handwriting) makes it a bit more confusing.
I don't know about HamNoSys. It's based on Stokoe, but it's far more complex (you could perhaps compare Stokoe and HamNoSys to the Spanish alphabet and the IPA -- Stokoe itself is relatively straightforward, but the precise way in which a specific series of characters is signed may differ slightly between signed languages, similar to how the pronounciation of the Latin alphabet sequence "calpricap" differs across languages although usually very similar; HamNoSys on the other hand is more precise)
Mark