dear george ananda ,
Having practiced buddhism for many years before coming to the vaisnava tradition, I understand your feeling there are many schools and many sometimes contradictory teachings and the argumrnts between schools over texts and practice were enough to put me off. however I feel that one can benifit greatly by sticking to the core teachings the four knoble truths and the eight fold path , as by perfection of the eight fold path one accheives all the teachings and may attain enlightenment by this practice alone . as it was the original discourse given by lord buddha I rely upon it above all texts, it has been handed down in all traditions as the core teaching . each tradition then has later discourses of lord buddha , first handed down , then written at a later date some centurys later . it is therefore difficult to safely vouch that they are the true words of lord buddha .
if you compare traditions it is easy to see that each has taken on its own character and the teachings very much reflect the culture and mentality of each comunity in which buddhism became established .Tibetan buddhism being highly influenced by indian mahayana buddhism and non buddhist tantric traditions , whilst retaining elements of the indiginous bon tradition , whilst theravada has a distinctly different flavor allthough relying on much the same original teachings it has fostered a very different motivation and application .
personaly I feel that each tradition has taken on a new character again as it has been taken up in the west , as you say "Tinted by " the different schools of thought it meets on the way , therefore it is constantly changing in small increments as it meets with other philosophies , there is a great danger that the orriginal message will be altered beyond the point which it was intended to convey , it is for this reason that I would stress the importance of reliance on the eight fold path