Before I answer the question posed above let me say that I think the legislature still has all the powers it ever had. All that is lacking is a legislature with enough members who actually understand the Constitution, their oaths of office, and who have the intestinal fortitude to simply exercise those powers.
Now to the question.
I think Madison is wrong here but must admit that I GREATLY fear a convention that is not strictly limited as to the issues it may address. I must also admit that I do not know just how the limits imposed on any such convention could be EFFECTIVELY enforced in practice.
If you go to Post #2 and click on the link to Federalist #43, you’ll find an essay at the end that lays out all the angles on a Convention for Proposing Amendments.