I was just recently reading the sufi texts I could find online and.. well, first of all they f**king rock.
they do, as you say, fecking rock. the thing to be aware of with sufi texts is that they are replete with symbolic levels and if you are unfamiliar with their taught tradition and the languages involved it can seem a bit new-age-happy-clappy. in fact, there are a fair number of people around who call themselves sufis who, imho, really aren't.
Secondly, I was struck by how the tradition not only pre-dates Islam (which is impossible in Islamic doctrine, but true nonetheless), but goes as far back as Persian mysticism (which is pre-history). What's the chances that it only embraced Islamic tradition out of necessity to survive through assimilation?
there are a number of opinions on this; i know of at least one (persian, i think) sufi school which definitely considers itself pre-islamic, in much the same sense that Truth is Universal and all that sort of thing. but the other ones i'm familiar with were set up post-islam, so obviously they are influenced by the fact that their founders and members were for the most part devoutly religious sunni and shia. i think you're being a teensy bit unfair to islam; they never claimed that Truth was inaccessible to humanity before the Qur'an, only that muhammad was the *last* prophet and that he was specifically sent to the arabs because they were in
jahiliyya, a "time of ignorance", as it were. everyone else got their own messengers from G!D.
the sufis have always been a bit on the controversial side and came in and out of fashion in the islamic world, rather like the jewish mystics. but yes, as you say, they're not entirely an islamic phenomenon, but in most cases they are islamic.
b'shalom
bananabrain