I think the present way the filibuster is being employed isn't consistent with the 'founders' original plan. The evidence I'd cite would be the perfunctory manner in which Congress enacted and could dispose of the rule as presently constructed if they wished. I really don't think the founders intended for the Senate to be so influential.
here's one argument from the NYT:
This change to the Constitution was not the result of, say, a formal amendment, but a procedural rule adopted in 1975: a revision of Senate Rule 22, which was the old cloture rule. Before 1975, it took two-thirds of the Senate to end a filibuster, but it was the “Mr. Smith Goes to Washington” filibuster: if senators wanted to stop a vote, they had to bring in the cots and the coffee and read from Grandma’s recipe for chicken soup until, unshaven, they keeled over from their own rhetorical exhaust.
For the record, nothing like Senate Rule 22 appears in the Constitution, nor was there unlimited debate until Vice President Aaron Burr presided over the Senate in the early 180os. In 1917, after a century of chaos, the Senate put in the old Rule 22 to stop unlimited filibusters. Because it was about stopping real, often distressing, floor debate, one might have been able to defend that rule under Article I, Section 5 of the Constitution, which says, “Each house may determine the rule of its proceedings.”
As revised in 1975, Senate Rule 22 seemed to be an improvement: it required 60 senators, not 67, to stop floor debate. But there also came a significant change in de facto Senate practice: to maintain a filibuster, senators no longer had to keep talking. Nowadays, they don’t even have to start; they just say they will, and that’s enough. Senators need not be on the floor at all. They can be at home watching Jimmy Stewart on cable. Senate Rule 22 now exists to cut off what are ghost filibusters, disembodied debates.
As a result, the supermajority vote no longer deserves any protection under Article I, Section 5 — if it ever did at all. It is instead a revision of Article I itself: not used to cut off debate, but to decide in effect whether to enact a law. The filibuster votes, which once occurred perhaps seven or eight times a whole Congressional session, now happen more than 100 times a term. But this routine use of supermajority voting is, at worst, unconstitutional and, at best, at odds with the founders’ intent.
read:
http://www.nytimes.com/2010/01/11/opinion/11geoghegan.html?pagewanted=print