Hi!
My friend from Guitartricks -Andrew Francis- did revision of English version of my article about two-handed tapping articulation, see:
http://adam.fulara.com/a/eind.php?g=eportato
This text is simmilar to Allan Holdsworth legato method - Allan don't use pull-offs at all :)))) Similar technique has Garsed and Lane, You can read about this in article:
http://www.ibreathemusic.com/play/article/111
There are two important diffrents:
-In PORTATO You do short breaks after each sound, so You can accent different notes in ascending hammer-ons. Holdsworth uses pick in this point.
-economy picking - in tapping we don't use pick at all so when You change string it sound different, than in Holdsworth's legato.
What You think?