Thanks for your thoughts on this. For what it's worth, I ended up installing Salsa top cross levers (from Velo Orange) on my Grand Jubile. Much pricier than the other obvious candidates, but aesthetic count and I wanted them silver to match my bars. And they are extremely nice; installation wasn't complicated; just make sure you have extra cable housing to play with, and I put in new cables too.
Having ridden with them now for about a week I would say they are a significant addition; they're perfect for the kind of upright cruising gently through suburban streets (and stop signs) that I do around here on a daily basis. I don't see that there's any problem with confusing muscle memory: when I ride on the tops my index fingers rest naturally on the levers, and so there there for a gentle slowing if I need them. And I tried some pretend emergency stops and they work at least as well as when riding on the hoods.
So, every day, in every day, biking just keeps getting better and better....